Isan language

Isan or Northeastern Thai () refers to the local development of the Lao language in Thailand, after the political split of the Lao-speaking world at the Mekong River, with the left bank eventually becoming modern Laos and the right bank the Isan region of Thailand (formerly known as Siam prior to 1932), after the conclusion of the Franco-Siamese War of 1893. The language is still referred to as Lao by native speakers. As a descendant of the Lao language, Isan is also a Lao-Phuthai language of the Southwestern branch of Tai languages in the Kra-Dai language family, most closely related to its parent language Lao and 'tribal' Tai languages such as Phuthai and Tai Yo. Isan is officially classified as a dialect of the Thai language by the Thai government; although Thai is a closely related Southwestern Tai language, it actually falls within the Chiang Saen languages. Thai and Lao (including Isan) are mutually intelligible with difficulty, as even though they share over 80% cognate vocabulary, Lao and Isan have a very different tonal pattern, vowel quality, manner of speaking and many very commonly used words that differ from Thai thus hampering inter-comprehension without prior exposure.
The Lao language has a long presence in Isan, arriving with migrants fleeing southern China sometime starting the 8th or 10th centuries that followed the river valleys into Southeast Asia. The region of what is now Laos and Isan was nominally united under the Lao kingdom of Lan Xang (1354–1707). After the fall of LanXang, the Lao splinter kingdoms became tributary states of Siam. During the late 18th and much of the 19th century, Siamese soldiers looking to weaken the power of the Lao kings carried out forced migrations of Lao from the left to the right bank, now Isan, impressing people for enslavement, "corvée" projects, the Siamese armies, or developing the dry Khorat Plateau for farming to feed the growing population. As a result of massive movements, Lao speakers comprise almost one-third of the population of Thailand and represent more than 80% of the population of Lao speakers overall. It is natively spoken by roughly 13-16 million (2005) people of Isan, although the total population of Isan speakers, including Isan people in other regions of Thailand, and those that speak it as a second language, likely exceeds 22 million.
The Lao language in Thailand was preserved due to the Isan region's large population, mountains that separated the region from the rest of the country, a conservative culture and ethnic appreciation of their local traditions. The language was officially banned from being referred to as the Lao language in official Thai documents at the turn of the 20th century. Assimilatory laws of the 1930s that promoted Thai nationalism, Central Thai culture and mandatory use of Standard Thai led to the region's inhabitants largely being bilingual and viewing themselves as Thai citizens and began a diglossic situation. Standard Thai is the sole language of education, government, national media, public announcements, official notices and public writing, and even gatherings of all Isan people, if done in an official or public context, are compelled to be in Thai, reserving Isan as the language of the home, agrarian economy and provincial life. The Tai Noi script was also banned, thus making Isan a spoken language, although an ad hoc system of using Thai script and spelling of cognate words is used in informal communication.
Isan is also a more agricultural area and one of the poorest, least developed regions of Thailand, with many Isan people having little education often leaving for Bangkok or other cities and even abroad for work, often employed as laborers, domestics, cooks, taxi drivers, construction and other menial jobs. Combined with historic open prejudice towards Isan people and their language, this has fueled a negative perception of the language. Despite its vigorous usage, since the mid-20th century, the language has been undergoing a slow relexification by Thai or language shift to Thai altogether, threatening the vitality of the language. However, with attitudes toward regional cultures becoming more relaxed in the late 20th century onwards, increased research into the language by Thai academics at Isan universities and an ethno-political stance often at odds with Bangkok, some efforts are beginning to take root to help stem the slow disappearance of the language, fostered by a growing awareness and appreciation of local culture, literature and history.
Classification.
Isan, as a variety of the Lao language, falls within the Lao-Phuthai group of languages, including its closest relatives, Phuthai (BGN/PCGN "Phouthai") and Tai Yo. Together with Northwestern Tai—which includes Shan, Ahom and most Dai languages of China, the Chiang Saen languages—which include Standard Thai, Khorat Thai and Tai Lanna—and Southern Tai form the Southwestern branch of Tai languages. Lao (including Isan) and Thai, although they occupy separate groups, are mutually intelligible and were pushed closer through contact and Khmer influence, but all Southwestern Tai languages are mutually intelligible to some degree. The Tai languages also include the languages of the Zhuang, which are split into the Northern and Central branches of the Tai languages. The Tai languages form a major division within the Kra-Dai language family, distantly related to other languages of southern China, such as the Hlai and Be languages of Hainan and the Kra and Kam-Sui languages on the Main and in neighbouring regions of northern Vietnam.
Within Thailand, the speech of the Isan people is officially classified as a 'Northeastern' dialect of the Thai language and is referred to as such in most official and academic works concerning the language produced in Thailand. The use of 'Northeastern Thai' to refer to the language is re-enforced internationally with the descriptors in the ISO 639-3 and "Glottolog" language codes. Outside of official and academic Thai contexts, Isan is usually classified as a particular sub-grouping of the Lao language, such as by speakers themselves and most linguists, or as a separate language closely related to Lao in light of its different orthography and Thai influences that distinguish it overall, such as its classification in "Glottolog" and "Ethnologue".
Exonyms.
In official and academic contexts within Thailand, Isan is treated as a dialect of the Thai language and referred to in Thai as "Phasa Thai Tawan Ok Chiang Neua" ( ), 'Northeastern Thai language', or "Phasa Thai Thin Isan" ( ), 'Thai language of the Isan region'. In common speech, Thais generally use the terms "Phasa Thai Isan" (), 'Isan Thai language' or 'Thai language of Isan', or simply "Phasa Isan" ( ), 'Isan language'. 'Isan' derives from which in turn is a derivative of "Īśāna" (), which in Sanskrit refers to both the 'northeast direction', i.e., northeast of Bangkok, as well as an aspect of Shiva as guardian of the northeastern direction. It also references Isanapura, capital of the Khmer kingdom of Chenla that ruled the region prior to the Tai migrations. 'Isan' initially only referred to what is now southern Isan but was later applied as a convenient appellation for the entire region, people and their language as it marked them as Thai and reduced the ambiguity of which Lao people were being referred to, but also to maintain distinction even when the term 'Lao' was no longer permitted as a census category by citizens of Siam.
Thai speakers may also casually refer to the language as "Phasa Lao" ( ), 'Lao language', but this is generally considered offensive by Isan people. As Isan people have suffered discrimination by Thai citizens from other regions, particularly Bangkok and the large Thai-Chinese minority, its use is considered very offensive, as 'Lao' is used as an insult, usually re-enforcing negative stereotypes of poor command of the Thai language, laziness, stupidity, poverty and religious zealots. The term 'Lao' is better avoided unless one is familiar with Isan people on intimate terms. The phrase "Phasa Ban Nok" () , which can translate as 'rural', 'upcountry' or 'provincial language' may also be used by Thai speakers to refer to the Isan language, but is also used for any rural, unsophisticated accent, even of Central Thai.
To Lao speakers in Laos, the language is acknowledged as "Phasa Lao" ( ), but is distinguished from the language of Laos by usages such as "Phasa Lao Isan" ( ), 'Isan Lao language' or 'Lao language of Isan' or "Phasa Thai Lao" ( ) which can mean 'Lao people's language', 'Lao Thai language' or 'Thailand's Lao language'. 'Lao' is also the general term in use by other linguistic minorities of the region, although in international languages, 'Isan' or translations of 'Northeastern Thai language' are used.
Endonyms.
Isan people traditionally refer to their language as "Phasa Lao" ( /pʰáː săː láːw/), 'Lao language', or "Phasa Tai Lao" ( /pʰáː săː láːw/), 'Lao people's language'. The language is also known as "Phasa Thai Lao" (), 'Lao Thai language' or 'Lao language of Thailand'. The term 'Lao' is derived from an ancient Kra-Dai loan word from the Austroastiac languages, *"k.ra:w" which signified a '(venerable) person' and is the ancestor of the not only 'Lao' (, ) in reference to the Lao people, Lao language or the country of Laos but also the third-person pronoun 'he'/'she' as well as "hao" (, , ), the plural first-person pronoun 'we'. 'Tai', 'Thai' and related forms 'Thay' and 'Dai' derive from another Austoasiatic loan word into Kra-Dai, *"k.riː" which also signified 'person' or 'free person'.
Due to prejudice and stigmatization of the spoken language by Thai people of other regions, Isan speakers only refer to themselves and their language as 'Lao' when in a comfortable environment where they can speak the language freely, such as anywhere in Isan or in the company of other Isan people in more private settings, such as a family home or groups of friends from the region visiting one another. To prevent confusion with Lao people of Laos and use a more neutral term, Isan people also use "Phasa Thai Isan" ( ) or simply "Phasa Isan" () when in mixed company or outside of Isan. Younger generations are more apt to forsake any Lao identity and have generally switched to the regional Isan designation for themselves and their language. The language is also known poetically and affectionately as "Phasa Ban Hao" (, ) which can signify 'our home language' or 'our village language'.
Geographical distribution.
The Isan language is the primary spoken language of households in the twenty provinces of Northeastern Thailand, also known as "Phak Isan" (), 'Isan region' or just "Isan". The region is mostly covered by the Khorat Plateau, which is generally flat, although there are some hilly areas. Mountain ranges separate the region from the rest of Thailand, such as the Phetchabun and Dong Phaya Yen ranges to the west and the Sankamphaeng to the southwest. The Thai border with Cambodia in southern Isan follows the ridgeline of the Dongrak mountains. The Khorat Plateau is separated by the Phu Phan Mountains into a northern region drained by the Loei and Songkhram rivers and a southern region drained by the Mun and its major tributary the Si. The water from these rivers flows into the Mekong River which for the most part serves as the border with Laos and the 'division' of the Isan and Lao languages, although this does occur in the written language. Isan speakers also spill into areas bordering the region, such as portions of Uttaradit and Phitsanulok provinces, particularly close to Isan and along the Mekong river, and a narrow sliver along the eastern edge of Phetchabun to the northwest and portions of Sa Kaeo and Phrachinburi provinces to the southwest.
History.
Separate development of the Isan language.
Integration Period (1893—1932).
After the French established their protectorate over the left bank Lao-speaking territories that became Laos during the conclusion of the Franco-Siamese War of 1893, the right bank was absorbed into Siam which was then ruled by King Wachirawut. To prevent further territorial concessions, the Siamese implemented a series of reforms that introduced Western concepts of statehood, administrative reforms and various measures to integrate the region which was until this point ruled as semi-autonomous out-lying territories nominally under the authority of the Lao kings. With the creation of provinces grouped into districts known as "monthon" (, , ), the power of local Lao princes of the "mueang" in tax collection and administration was moved and replaced by crown-appointed governors from Bangkok which removed the official use of Lao written in Tai Noi in local administration. To achieve this, King Wachirawut had the help of his brother, Prince Damrongrachanuphap who recommended the system. The end of local autonomy and the presence of foreign troops led the Lao people to rebel under the influence of millennialist cult leaders or "phu mi bun" (, , ) during the Holy Man's Rebellion (1901—1902), the last united Lao resistance to Siamese rule, but the rebellion was brutally suppressed by Siamese troops and the reforms were fully implemented in the region shortly afterward.
Further reforms were implemented to assimilate and integrate the people of the "Lao "Monthon"" into Siam. References to the 'Lao' and many cities and towns were renamed, such as the former districts Monthon Lao Gao and Monthon Lao Phuan which were renamed as 'Monthon Ubon' and 'Monthon Udon', respectively, shortly after their creation in 1912. Self-designation as Lao in the census was banned after 1907, with the Lao forced to declare themselves as Thai and speakers of a Thai dialect. The unofficial use of Lao to refer to them was discouraged, and the term 'Isan', originally just a name of the southern part of the 'Lao "Monthon"', was extended to the entire region, its primary ethnic group and language. The name change and replacement of the Lao language by Thai at the administrative level and reforms to implement Thai had very little effect as the region's large Lao population and isolation prevented quick implementation. Monks still taught young boys to read the Tai Noi script written on palm-leaf manuscripts since there were no schools, passages from old literature were often read during festivals and traveling troupes of "mo lam" and shadow puppet performers relied on written manuscripts for the lyrics to poetry and old stories set to song and accompanied by the "khaen" alone or alongside other local instruments. Mountains, lack of roads, large areas without access to water during the dry season and flooding in the wet season continued to shield the Isan people and their language from direct Thai-language influence.
Thaification (1930s–1960s).
Suppression of the Isan language came with the 'Thai cultural mandates' and other reforms that aimed to elevate Central Thai culture and language, reverence to the monarchy and the symbols of state and complete integration into Thailand, known as 'Thaification'. Most of these reforms were implemented by Plaek Phibunsongkhram, who changed the English name of Siam to 'Thailand' and whose ultra-nationalistic policies would mark Thailand during his rule from 1938 to 1944 and 1948–1957. These policies implemented an official diglossia. Isan was removed from public and official discourse to make way for Thai and the written language was banned, relegating Isan to an unwritten language of the home. Public schools, which finally were built in the region, focussed heavily on indoctrinating Isan people to revere the Thai monarchy, loyalty to the state and its symbols and mastery of the Thai language, with Isan treated as an inferior dialect. Pride in the language was erased as students were punished or humiliated for using the language in the classroom or writing in Tai Noi, planting the seed for future language shift as the region became bilingual.
The old written language and the rich literature written in it were banned and was not discussed in schools. Numerous temples had their libraries seized and destroyed, replacing the old Lao religious texts, local histories, literature and poetry collections with Thai-script, Thai-centric manuscripts. The public schools also dismissed the old monks from their role as educators unless they complied with the new curriculum. This severed the Isan people from knowledge of their written language, shared literary history and ability to communicate via writing with the left bank Lao. In tandem with its removal from education and official contexts, the Thai language made a greater appearance in people's lives with the extension of the railroad to Ubon and Khon Kaen and with it the telegraph, radio and a larger number of Thai civil servants, teachers and government officials in the region that did not learn the local language.
Words for new technologies and the political realities of belonging to the Thai state arrived from Thai, including words of English and Chinese (primarily Teochew) origin, as well as neologisms created from Sanskrit roots. Laos, still under French rule, turned to French, Vietnamese, repurposing of old Lao vocabulary as well as Sanskrit-derived coinages that were generally the same, although not always, as those that developed in Thai. For example, the word or aeroplane (UK)/airplane (US) in Isan was "huea bin" ( ) 'flying boat', but was generally replaced by Thai-influenced "khrueang bin" ( ) 'flying machine', whereas Lao retained "hua bin" ( ) RTSG "huea bin". Similarly, a game of billiards in Isan is ( from English via Thai; whereas on the left bank, people play "biya" ( ) from French "billard" . Despite this slow shift, the spoken language maintained its Lao features since most of the population was still engaged in agriculture, where Thai was not needed, thus many Isan people never mastered Thai fully even if they used it as a written language and understood it fine.
1960s to Present.
The language shift to Thai and the increased influence of the Thai language really came to the fore in the 1960s due to several factors. Roads were finally built into the region, making Isan no longer unreachable for much of the year, and the arrival of television with its popular news broadcasts and soap operas penetrated into people's homes at this time. As lands new lands to clear for cultivation were no longer available, urbanization began to occur, as well as the massive seasonal migration of Isan people to Bangkok during the dry season, taking advantage of the economic boom occurring in Thailand with increased western investment due to its more stable, non-communist government and openness. Having improved their Thai during employment in Bangkok, the Isan people returned to their villages, introducing the Bangkok slang words back home and peppering their speech with more and more Thai words.
Around the 1990s, although the perceived political oppression continues and Thaification policies remain, attitudes towards regional languages relaxed. Academics at Isan universities began exploring the local language, history, culture and other folklore, publishing works that helped bring serious attention to preserving the Lao features of the language and landscape, albeit under an Isan banner. Students can participate in clubs that promote local music, sung in the local Lao language, or local dances native to the area. Knowledge about the history of the region and its long neglect and abuse by Siamese authorities and resurrection of pride in local culture are coming to the fore, increasing expressions of 'Isan-ness' in the region. However, Thaification policies and the language shift to Thai continue unabated. Recognition of the Isan language as an important regional language of Thailand did not provide any funding for its preservation or maintenance other than a token of acknowledgment of its existence.
Language status.
Legal status.
The status of the Isan language is explained by Ethnologue as the "'de facto" language of provincial identity' which 'is the language of identity for citizens of the province, but this is not mandated by law. Neither is it developed enough or known enough to function as the language of government business.' Although Thailand does recognize the existence of the Isan region as the primary regional language, this is a token gesture and does not elevate or promote the Isan language in any degree. In fact, the Thaification policies that removed Isan from the formal and public sphere and prevented Isan people from using the Tai Noi script are still active and mastery of Thai is required for participation in national life and economic and social advancement.
Unlike in Laos, where speakers make up only half the population and usually are found only in narrow bands hugging riparian valleys, the language is nevertheless official, used in all government and media and all registers of the language. Although Laos is bombarded with Thai media and many Lao speakers in Laos are also able to understand and read Thai, although some are unable to speak it and write it, the schools and government policy and the Lao people's desire to preserve their language have prevented the Thai relexification occurring in Isan.
Spoken status.
The spoken language is currently at Stage VIA, or 'vigorous', on the EGIDS scale developed by Joshua Fishman, which is defined by "Ethnologue" as a language that is used for 'face-to-face communication by all generations and the situation is sustainable'. According to data from 1983, 88 percent of Isan households were predominantly Isan speaking, with 11 percent using both Thai and Isan at home, and only one percent using exclusively Thai. Although this sounds promising for the continued future of the Isan language, there are many signs indicating that the language could reach Stage VIB, or 'threatened', which is defined as a 'language used for face-to-face communication within all generations, but it is losing users. As a strong command of Thai is necessary for advancement in most government, academic, and professional realms, and in order to work in areas like Bangkok where Isan is not the local language.
The language suffers from a negative perception and diglossia, so speakers have to limit their use of the language to comfortable, informal settings. Parents often view the language as a detriment to the betterment of their children, who must master Standard Thai to advance in school or career paths outside of agriculture. The use of the Thai script, spelling cognate words in Isan as they are in Thai, also gives a false perception of the dialectal subordination of Isan and the errors of Isan pronunciation which deviate from Thai. As a result, a generational gap has arisen with old speakers using normative Lao and younger speakers using a very 'Thaified' version of Isan, increased code-switching or outright exclusive use of Thai. Many linguists and scholars of the Isan language believe that Thai relexification cannot be halted unless the script is returned, but this has little public or government support.
Written language usage and vitality.
The written language is currently at Stage IX, which on the EGIDS scale is a 'language [that] serves as a reminder of heritage identity for an ethnic community, but no one has more than symbolic proficiency'. This applies to both the "Tai Noi" script used for secular literature and the "Tua Tham" script previously used for Buddhist texts. Only a handful of people of very advanced age and caretakers of monasteries whose libraries were not destroyed during the Thaification implementation in the 1930s are able to read either script. Evidence for the use of the written language is hard to find, but well-worn murals of very old temples often have small bits of writing in the old script.
In Laos, the orthography is a direct descendant of "Tai Noi" and continues its role as the official written language of the Lao language of the left bank as well as the script used to transcribe minority languages. The Lao written language has unified the dialects to some extent as well, as though the differences between dialects are sharper in Laos than Isan, one common writing system unites them.
Language threats.
Negative perceptions.
Acknowledgment of the unique history of the Isan language and the fact it is derived from a closely related albeit separate language is lacking, with the official and public position being that the language is a dialect of Thai. As a result of the great difference from Thai, based on tone, nasal vowels of a different quality and a special set of Lao vocabulary unfamiliar to Thai speakers, it is considered an 'inferior form of Thai' as opposed to its own separate language. The traditional avoidance of the language in the formal sphere re-enforces the superiority of Thai, which the Isan people have internalized to the point many do not have high opinions of their first language. Combined with vocabulary retentions, many of which sound oddly archaic or have become pejorative in Standard Thai, perpetuate the myth and negative perception of Isan as an uncouth language of rural poverty and hard agricultural life. Due to associations with Laos, the language was also viewed as a potential fifth column for Lao irredentism and the spread of communism into Thailand. It was in the recent past quite common for Isan people to be corrected or ridiculed when they spoke because of their incomplete mastery of Standard Thai.
In polling of language favorability amongst the general population of Thailand, the Isan language ranks last after Standard Thai and the primary Thai dialect of the other regions. As a result of the need for Standard Thai proficiency in order to have better educational and employment prospects and avoid discrimination, anecdotal evidence suggests that more and more Isan children are being raised in the Thai language and are discouraged from using the local language at home. The Thai language has already begun to displace the predominance of Isan in the major market towns, in part because they are often also administrative centers, and in some major cities, universities have attracted students from other regions.
Code-switching.
Since the late 1930s, Isan has been a bilingual area, with most people using Isan at home and in the village, but due to diglossia, switching to Thai for school, work and formal situations. Like all bilingual societies, Isan speakers often code-switch in and out of the Thai language. For example, in an analysis of the eighty-eight volumes of the comic 'Hin the Mouse' "in the city", the Thai language was used 62.91 percent of the time to properly quote someone—such as someone that speaks Thai, 21.19 percent of the time to provide further explanation and 8.61 percent of the time to re-iterate a previous statement for clarification. There are seven areas where the Thai language is employed, aside from direct quotation, such as the following: explanations, interjections, Thai culture, emphasis, re-iterations and jokes.
Although some Isan people may not speak the language well, Thai is a convenient language of clarification, especially between Isan speakers of different dialects that may be unfamiliar with local terms of the other speaker. As Isan does not exist in formal, technical, political or academic domains, it is generally more comfortable for Isan speakers to use Thai in these areas as a result of the diglossia, with many Isan speakers unaware or unfamiliar with native terms and "belles-lettres" that are still used in contemporary Lao. Thai is also sometimes used to avoid Isan features that are stigmatized in Thai, such as retention of vocabulary that is pejorative or archaic as well as Lao pronunciations of cognate words that sound 'folksy'. Despite the fact that code-switching is a natural phenomenon, younger generations are blurring the distinction between languages, using more Thai-like features and as they forget to switch back to Isan, language shift takes hold.
Thai-influenced language shift.
The Thai language may not be the primary language of Isan, but Isan people are in constant exposure to it. It is required to watch the ever-popular soap operas, news, and sports broadcasts or sing popular songs, most of it produced in Bangkok or at least in its accent. Thai is also needed as a written language for instructions, to read labels on packages, road signs, newspapers and books. Isan children who may struggle to acquire the language, are forced to learn the language as part of compulsory education and often when they are older, for employment. Although attitudes towards regional cultures and languages began to relax in the late 1980s, the legal and social pressures of Thaification and the need for Thai to participate in daily life and wider society continue. The influence of Thai aside, anecdotal evidence suggests that many older Isan lament the corruption of the spoken language spoken by younger generations and that the younger generations are no longer familiar with the traditional Lao forms used by previous generations.
In a 2016 study of language shift, villagers in an Isan-speaking village were divided by age and asked to respond to various questionnaires to determine lexical usage of Lao terms, with those born prior to 1955, those born between 1965 and 1990 and those born after 1990. The results show what would be expected of a language undergoing language shift. As Isan and Thai already have a similar grammatical structure and syntax, the main variance is in lexical shift, essentially the replacement of Isan vocabulary. The oldest generation, at the time in their 60s or older, uses very normative Lao features little different than those found in Laos. The middle generations, ranging from 35 to 50 years of age, had a greater prevalence of Thai vocabulary, but overall maintained a traditional Isan lexicon, with the Thai terms usually not the primary spoken forms. The youngest generation, although still arguably using very many Lao phrases and vocabulary, had a remarkable replacement of Isan vocabulary, with Thai forms becoming either the primary variant or replacing the Isan word altogether. Similarly, when Isan usage has two variants, generally a common one not understood in Thai and another that is usually a cognate, younger speakers tend to use the cognates with greater frequency, pushing their speech to Thai as older speakers will use them in variance.
Thai loan words were generally localized in pronunciation, easing them into the flow of Isan conversation and unnoticeable to most but the oldest members of the community that preserve 'proper Isan' usage. Although the youngest generation was still speaking a distinct language, each generation brings the increased risk of the Isan language's extinction as it becomes relexified to the point of no longer being a separate language but a dialect of Thai with some Lao influence. The lack of official usage, official support for its maintenance and lack of language prestige hinder attempts to revitalize or strengthen the language against the advance of Thai.
Continued survival.
The development of 'Isan' identity and a resurgence in attention to the language has brought increased attention and study of the language. Academics at universities are now offering courses in the language and its grammar, conducting research into the old literature archives that were preserved. Digitizing palm-leaf manuscripts and providing Thai-script transcription is being conducted as a way to both preserve the rapidly decaying documents and re-introduce them to the public. The language can be heard on national television during off-peak hours, when music videos featuring many Isan artists of molam and Isan adaptations of Central Thai luk thung music. In 2003, HRH Princess Royal Sirinthon was the patron of the Thai Youth Mo Lam Competition.
Phonology.
Consonants.
Initials.
Isan shares its consonant inventory with the Lao language whence it derives. The plosive and affricate consonants can be further divided into three voice-onset times of voiced, tenuis and aspirated consonants. For example, Isan has the plosive set of voiced /b/, tenuis /p/ which is like the 'p' in 'spin' and aspirated /pʰ/ like the 'p' in 'puff'. Isan and Lao lack the sound /tɕʰ/ and its allophone /ʃ/ of Thai, replacing these sounds with /s/ in analogous environments. Similarly, /r/ is rare. Words in Isan and Lao cognate to Thai word with /r/ have either /h/ or /l/ in their place, although educated speakers in Isan or Laos may pronounce some words with /r/. In Thai, words with /r/ may be pronounced as /l/ in casual environments although this is frowned upon in formal or cultivated speech.
Unlike Thai, Isan and Lao have a /j/-/ɲ/ distinction, whereas cognate words from Isan and Lao with /ɲ/ are all /j/ in Thai. Substitution of /w/ with /ʋ/, which is not used in Thai, is common in large areas of both Laos and Isan but is not universal in either region, but is particularly associated with areas influenced by Vientiane and Central Lao dialects. The glottal stop occurs any time a word begins with a vowel, which is always built around a null consonant.
Clusters.
Consonant clusters are rare in Isan and Lao and were lost in pronunciation before the time writing in Tai Noi began, although some remnants of how words were spelled in the oldest documents suggest that some words may have retained them before the simplification process. As a result, in traditional Isan and Lao pronunciation, only /kw/ and /kʰw/ as consonant clusters. Due to a unique phonological process of diphthongization, these clusters are lost when they occur before the vowels /aC/, /am/, /aː/ and /aːj/, limiting environments where these can occur. Thus the word for 'wide' is "gwang" ( , cf. BGN/PCGN "kouang") and not the true cluster as occurs in Thai and is suggested by spelling, ( ). Isan speakers, however, spell words etymologically according to their Thai pronunciation if they are cognate words, thus Isan speakers write the clusters but traditionally do not pronounce them, although they might in formal situations. In Laos, the pronunciation and spelling do not indicate the Thai clusters, and cognate words are spelled and pronounced without them, although a handful of Sanskrit and Khmer vocabulary may be pronounced in 'Thai' fashion by older, educated speakers of the Lao diaspora.
Finals.
Isan shares with both Lao and Thai a restrictive set of permissible consonant sounds at the end of a syllable or word. Isan, using its current method of writing according to Thai etymological spelling, preserves the spelling to imply the former sound of borrowed loan words even if the pronunciation has been assimilated. Due to spelling reforms in Laos, the letters that can end a word were restricted to a special set of letters, but older writers and those in the Lao diaspora occasionally use some of the more etymological spellings.
In pronunciation, all plosive sounds are unreleased, as a result, there is no voicing of final consonants or any release of air. The finals /p/, /t/ and /k/ are thus actually pronounced , , and , respectively.
Vowels.
The vowel structure of Isan is the same as the central and southern Lao dialects of Laos. The vowel quality is also similar to Thai, but differs in that the two back vowels, close back unrounded vowel /ɯ/ and the close-mid back unrounded vowel /ɤ/, centralized as the close central unrounded vowel /ɨ/ and the mid central vowel /ə/, respectively, as well as in diphthongs that may include these sounds. To Thai speakers, Isan and Lao vowels tend to have a nasal quality.
In many cases, especially diphthongs with /u/ as first element is lengthened in Isan as it is in Standard Lao, so that the word "tua" which means 'body' (, written the same in Isan) is pronounced in Thai but in Isan as , similar to . The symbol '◌' indicates the required presence of a consonant, or for words that begin with a vowel sound, the 'null consonant' 'อ' or its Lao equivalent, 'ອ', which in words that begin with a vowel, represents the glottal stop /ʔ/. Short vowels that end with '◌ะ' or Lao '◌ະ' also end with a glottal stop.
Thai and Lao are both abugida scripts, so certain vowels are pronounced without being written, taking the form of /a/ in open syllables and /o/ in closed syllables, i.e., ending in a consonant. For example, the Khmer loan word "phanom" or 'hill' found in many place names in Isan is or 'PH-N-M' but pronounced , with 'PH' as the open syllable and 'N-M' as the closed syllable. In Lao orthography, inherited from Tai Noi, closed syllables are marked with a 'ົ' over the consonants and the /a/ of open syllables was unwritten, thus or 'Ph-N-o-M'. In current practice as a result of spelling reforms, all vowels are written out and in modern or 'Ph-a-N-o-M' is more common thus modern Lao is no longer a true abugida.
Vowel length.
Vowels usually exist in long-short pairs determined by vowel length which is phonemic, but vowel length is not indicated in the RTSG romanization used in Thai or the BGN/PCGN French-based scheme commonly used in Laos. The Isan word romanized as "khao" can represent both , 'he' or 'she', and , 'white' which corresponds to and , respectively, which are also romanized as "khao". In these cases, the pairs of words have the same tone and pronunciation and are differentiated solely by vowel length.
Special vowels.
As Isan is written in Thai, it also has the following symbols not found in the Lao script or its predecessor, Tai Noi. The letters are based on vocalic consonants used in Sanskrit, given the one-to-one letter correspondence of Thai to Sanskrit, although the last two letters are quite rare, as their equivalent Sanskrit sounds only occur in a few, ancient words and thus are functionally obsolete in Thai. The first symbol 'ฤ' is common in many Sanskrit and Pali words and 'ฤๅ' less so, but does occur as the primary spelling for the Thai adaptation of Sanskrit 'rishi' and "treu" ( or ), a very rare Khmer loan word for 'fish' only found in ancient poetry.
In the past, prior to the turn of the twentieth century, it was common for writers to substitute these letters in native vocabulary that contained similar sounds as a shorthand that was acceptable in writing at the time. For example, the conjunction 'or' ( "reu", cf. "lu") was often written such as in 'เขาไปบ้านแล้วหรือยัง' (Did he go home yet or not?) formerly written 'เขาไปบ้านแล้วฤยัง'. The practice had become obsolete by the time that Isan speakers began adopting Thai writing, but Isan speakers are likely exposed to it in school when studying Thai literature. These letters did not occur in Tai Noi or the modern Lao alphabet, and equivalent words of Sanskrit origin are spelled out with other letters. Isan speakers historically, and many still do, use the Lao pronunciation of these words.
Grammar.
Isan words are not inflected, declined, conjugated, making Isan, like Lao and Thai, an analytic language. Special particle words function in lieu of prefixes and suffixes to mark verb tense. The majority of Isan words are monosyllabic, but compound words and numerous other very common words exist that are not. Topologically, Isan is a subject–verb–object (SVO) language, although the subject is often dropped. Word order is an important feature of the language.
Although in formal situations, standard Thai is often used, formality is marked in Isan by polite particles attached to the end of statements, and use of formal pronouns. Compared to Thai, Isan sounds very formal as pronouns are used with greater frequency, which occurs in formal Thai, but is more direct and simple compared to Thai. The ending particles เด้อ (doe, dɤː) or เด (de, deː) function much like ครับ (khrap, kʰráp), used by males, and คะ (kha, kʰaʔ), used by females, in Thai. (Isan speakers sometimes use the Thai particles in place of or after เด้อ or เด.) Negative statements often end in ดอก (dok, dɔ̀ːk), which can also be followed by the particle เด้อ and its variant.
Nouns.
Nouns in Isan are not marked for plurality, gender or case and do not require an indefinite or definite article. Some words, mainly inherited from Sanskrit or Pali, have separate forms for male or female, such as "thewa" ( , cf. BGN/PCGN "théva"), 'god' or 'angel' (masculine) and "thewi" ( , cf. BGN/PCGN "thévi"), 'goddess' or 'angel' (feminine) which derives from masculine "deva" ( and feminine "devī" ( ). This is also common in names of Sanskrit origin, such as masculine "Arun" ( , cf. BGN/PCGN "Aloun"/"Aroun") and feminine "Aruni" ( , cf. BGN/PCGN "Arouni"/"Alounee") which derives from "Arun" ) and "Arunī" , respectively. In native Tai words which usually do not distinguish gender, animals will take the suffixes "phu" ( , cf. BGN/PCGN "phou") or "mae" ( , cf. BGN/PCGN "mè"). For example, a cat in general is "maew" ( , cf. BGN/PCGN "mèo"), but a tomcat is "maew phou" () and a queen (female cat) is "maew mae" (), respectively.
Classifiers.
Verbs are easily made into nouns by adding the prefixes ความ (khwam/kʰwaːm) and การ (kan/kːan) before verbs that express abstract actions and verbs that express physical actions, respectively. Adjectives and adverbs, which can function as complete predicates, only use ความ. 
Pronouns.
Isan traditionally uses the Lao-style pronouns, although in formal contexts, the Thai pronouns are sometimes substituted as speakers adjust to the socially mandated use of Standard Thai in very formal events. Although all the Tai languages are pro-drop languages that omit pronouns if their use is unnecessary due to context, especially in informal contexts, but they are restored in more careful speech. Compared to Thai, Isan and Lao frequently use the first- and second-person pronouns and rarely drop them in speech which can sometimes seem more formal and distant. More common is to substitute pronouns with titles of professions or extension of kinship terms based on age, thus it is very common for lovers or close friends to call each other 'brother' and 'sister' and to address the very elderly as 'grandfather' or 'grandmother'.
To turn a pronoun into a plural, it is most commonly prefixed with "mu" ( , cf. BGN/PCGN "mou") but the variants "tu" ( , cf. BGN/PCGN "tou") and "phuak" ( , cf. BGN/PCGN "phouak") are also used by some speakers. These can also be used for the word "hao", 'we', in the sense of 'all of us' for extra emphasis. The vulgar pronouns are used as a mark of close relationship, such as long-standing childhood friends or siblings and can be used publicly, but they can never be used outside of these relationships as they often change statements into very pejorative, crude or inflammatory remarks.
Adjectives and adverbs.
There is no general distinction between adjectives and adverbs, and words of this category serve both functions and can even modify each other. Duplication is used to indicate greater intensity. Only one word can be duplicated per phrase. Adjectives always come after the noun they modify; adverbs may come before or after the verb depending on the word. There is usually no copula to link a noun to an adjective.
Comparatives take the form "A X กว่า B" (kwa, kwaː), A is more X than B. The superlative is expressed as "A X ที่สุด (thisut, tʰiːsut), A is most X.
Because adjectives or adverbs can be used as predicates, the particles that modify verbs are also used.
Verbs.
Verbs are not declined for voice, number, or tense. To indicate tenses, particles can be used, but it is also very common just to use words that indicate the time frame, such as พรุ่งนี้ (phung ni, pʰuŋ niː) "tomorrow" or มื้อวานนี้ (meu wan ni, mɯː vaːn niː) "yesterday."
Negation: Negation is indicated by placing บ่ (bo, bɔː) before the word being negated. 
Future tense: Future tense is indicated by placing the particles จะ (cha, tɕaʔ) or ซิ (si, siː) before the verb.
Past tense: Past tense is indicated by either placing ได้ (dai, daj) before the verb or แล้ว (laew, lɛːw) after the verb or even using both in tandem for emphasis. แล้ว is the more common one, and can be used to indicate completed actions or current actions of the immediate past. ได้ is often used with negative statements and never for present action.
Present progressive: To indicate an ongoing action, กำลัง (kamlang, kam.laŋ) can be used before the verb or อยู่ (yu, juː) after the verb. These can also be combined for emphasis. In Isan and Lao, พวม (phuam, pʰuam) is often used instead of กำลัง.
The verb 'to be' can be expressed in many ways. In use as a copula, it is often dropped between nouns and adjectives. Compare English "She is pretty" and Isan สาวงาม (literally "lady pretty"). There are two copulas used in Isan, as in Lao, one for things relating to people, เป็น (pen, pen), and one for objects and animals, แม่น (maen, mɛːn). 
Questions and answers.
Unlike English, which indicates questions by a rising tone, or Spanish, which changes the order of the sentences to achieve the same result, Isan uses question-tag words. The use of question words makes use of the question mark (?) redundant in Isan.
General yes/no questions end in บ่ (same as บ่, "no, not").
Other question words
Answers to questions usually just involve repetition of the verb and any nouns for clarification.
Words asked with a negative can be confusing and should be avoided. The response, even though without the negation, will still be negated due to the nature of the question.
Vocabulary.
The Tai languages of Thailand and Laos share a large corpus of cognate, native vocabulary. They also share many common words and neologisms that were derived from Sanskrit, Pali, Mon and Khmer and other indigenous inhabitants to Indochina. However, there are traits that distinguish Isan both from Thai and its Lao parent language.
Isan is clearly differentiated from Thai by its Lao intonation and vocabulary. However, Isan differs from Lao in that the former has more English and Chinese loanwords, via Thai, not to mention large amounts of Thai influence. The Lao adopted French and Vietnamese loanwords as a legacy of French Indochina. Other differences between Isan and Lao include terminology that reflects the social and political separation since 1893 as well as differences in neologisms created after this. These differences, and a few very small deviations for certain common words, do not, however, diminish nor erase the Lao characters of the language.
A small handful of lexical items are unique to Isan and not commonly found in standard Lao, but may exist in other Lao dialects. Some of these words exist alongside more typically Lao or Thai usages.
Dialects.
Although Isan is treated separately from the Lao language of Laos due to its use of the Thai script, political sensitivity and the influence of the Thai language, dialectal isoglosses crisscross the Mekong River, mirroring the downstream migration of the Lao people as well as the settlement of Isan from the east to west, as people were forced to the right bank. Isan can be broken up into at least fourteen varieties, based on small differentiations in tonal quality and distribution as well as small lexical items, but these can be grouped into the same five dialectal regions of Laos. As a result of the movements, Isan varieties are often more similar to the Lao varieties spoken on the opposite banks of the Mekong than to other Isan people up- or downstream although Western Lao, formed from the merger of peoples from different Lao regions, does not occur in Laos and is only found in Isan. 
Isan may have had historical leveling processes. The settlement of the region's interior areas led to dialect mixing and the development of transitional areas. The Vientiane dialect also likely had a major role in bringing Isan varieties closer. The provinces of Loei, Nong Khai and Bueang Kan border areas of Laos where Vientiane Lao is spoken, and together with Nong Bua Lamphu and much of Udon Thani, were long settled by Lao speakers of these dialects from the time of Lan Xang as well as the Kingdom of Vientiane. The destruction of Vientiane and the forced movement of almost the entire population of the city and surrounding region after the Lao rebellion greatly increased the population of Isan, with these Lao people settled across the region.
Writing systems.
Tai Noi script.
The original writing system was the "Akson Tai Noi" ( , cf. BGN/PCGN "Akson Tai Noy"), 'Little Tai alphabet' or "To Lao" ( , cf. ), which in contemporary Isan and Lao would be "Tua Lao" ( and , respectively, or 'Lao letters.' In Laos, the script is referred to in academic settings as the "Akson Lao Deum" ( , cf. RTGS "Akson Lao Doem") or 'Original Lao script.' The contemporary Lao script is a direct descendant and has preserved the basic letter shapes. The similarity between the modern Thai alphabet and the old and new Lao alphabets is because both scripts derived from a common ancestral Tai script of what is now northern Thailand which was an adaptation of the Khmer script, rounded by the influence of the Mon script, all of which are descendants of the Pallava script of southern India.
Thai alphabet.
The ban on the "Tai Noi" script in the 1930s led to the adoption of writing in Thai with the Thai script. Very quickly, the Isan people adopted an "ad hoc" system of using Thai to record the spoken language, using etymological spelling for cognate words but spelling Lao words not found in Thai, and with no known Khmer or Indic etymology, similarly to as they would be in the Lao script. This system remains in informal use today, often seen in letters, text messages, social media posts, lyrics to songs in the Isan language, transcription of Isan dialogue and personal notes.
'Lao'-ized spelling.
There are two aspects of Lao phonology inherited in Isan that native speakers will substitute different letters to represent the proper sound.
Proto-Southwestern Tai initial /r/ > /h/
Loss of Proto-Southwestern Tai /tɕʰ/ by merger with /s/ in Lao
Although it is not universal, Isan speakers may also employ the rare tone marks to record idiosyncratic or to record the accent of a speaker, in regards to tone since most Lao dialects have six instead of five tones, although the shapes of the tone contours and the rules between varieties are distinct from each other and Thai.
Special tone marks
Orthographical problems.
The Thai script and etymological Thai spelling is detrimental on several fronts. For those that wish to learn the Isan language, it makes the language look like Thai with some strange words as it does not record the unique sounds of the Isan language that are not distinguished in Thai. Isan tonal patterns are markedly distinct from Thai, but the Thai script is taught according to Thai tone rules, leading Thai speakers to mispronounce the tones of a native speaker. The deviations and similarity to Thai make it appear that Isan is a rural dialect instead of its own language with a separate history.
No orthographical distinction of /ɲ/ and /j/
Incomplete representation of /tɕʰ/ > /s/
Substitution of Thai spellings and suppression of non-Thai forms
Consonant clusters that do not exist in Lao
Etymological spelling of Sanskrit loan words vs. Lao phonetical spelling
Tai Tham.
The "Tai Tham" script ( RTGS "akson Tai Tham", cf. ) were also historically known simply as "tua tham" ( , cf. BGN/PCGN "toua tham") or 'dharma letters'. The script is the same as used to write Tai Lanna (Kham Mueang), Tai Lue, Tai Khoen and shares similarities with the Burmese script, all of which are ultimately derived from the Old Mon script. "Tai Tham" was introduced during the reign of Setthathirath who although a prince of Lan Xang, was first crowned king of Lan Na. The dynastic union allowed easy movement of monks from Lan Xang that came to copy the temple libraries to bring back home.
As the name suggests, its use in Lao was restricted to religious literature, either used to transcribe Pali, or religious treatises written in Lao intended solely for the clergy. Religious instructional materials and prayer books dedicated to the laity were written in "Tai Noi" instead. As a result, only a few people outside the temples were literate in the script. In Isan, evidence of the script includes two stone inscriptions, such as the one housed at "Wat Tham Suwannakhuha" in Nong Bua Lamphu, dated to 1564, and another from "Wat Mahaphon" in Maha Sarakham from the same period. Most of the script is recorded on palm-leaf manuscripts, many of which were destroyed during the 'Thaification' purges of the 1930s; contemporaneously this period of Thai nationalization also ended its use as the primary written language in Northern Thailand.
Khom script.
 The Khom script (อักษรขอม , cf. Lao ອັກສອນຂອມ, "Aksone Khom") was not generally used to write the ancient Lao language of Isan, but was often used to write Pali texts, or Brahmanic rituals often introduced via the Khmer culture. "Khom" is the ancient Tai word for the Khmer people, who once populated and ruled much of the area before Tai migration and the assimilation of the local people to Tai languages. It was generally not used to write the Lao language "per se", but was often found in temple inscriptions, used in texts that preserve Brahmanic mantras and ceremonies, local mantras adopted for use in Tai animistic religion and other things usually concerned with Buddhism, Brahmanism or black magic, such as yantras and "sakyan" tattoos.
Overview of the relationship to Thai.
Although Thai and Lao are mutually intelligible, Thai speakers without previous exposure to the Isan language encounter several difficulties parsing the spoken language. Differences were enough that the 2005 film "Yam Yasothon" ( "Yaem Yasothon" (, ) which takes places in the Isan countryside and features a predominately Isan dialogue, was shown with Thai-language subtitles, similar to the way the 1996 Scottish film "Trainspotting" was also subtitled for North American audiences. Isan, written according to Thai etymological spelling, is fairly legible to Thai as the two languages share more than eighty percent cognate vocabulary, similar to the relationship between Spanish and Portuguese as changes in the meanings of terms, retention of archaisms, slightly different grammar and some vocabulary differences blur the close relationship.
The relationship is asymmetric, with Isan speakers able to understand spoken and written Thai quite well due to its mandatory use in school and the popularity of Thai media and participation in Thai society, but many Isan students suffer the shock of switching from the Isan language of the home to the Central Thai-only primary school.
False cognates.
Many Isan (and Lao) terms are very similar to words that are profane, vulgar or insulting in the Thai language, features which are much deprecated. Isan uses อี่ (, cf. Lao: ອີ່) and อ้าย (, cf. Lao: ອ້າຍ/archaic ອ້າຽ), to refer to young girls and slightly older boys, respectively. In Thai, the similarly sounding อี, "i" () and ไอ้, "ai" () are often prefixed before a woman's or man's name, respectively, or alone or in phrases which are considered extremely vulgar and insulting. These taboo expressions such as อีตัว "i tua", "whore" () and ไอ้บ้า, "ai ba", "son of a bitch" ().
In Isan and Lao, these prefixes are used in innocent ways as it does not carry the same connotation, even though they share these insults with Thai. In Isan, it is quite common to refer to a young girl named 'Nok' as "I Nok" (อี่นก, cf. Lao ອີ່ນົກ "I Nôk" or to address one's mother and father as "i mae" (อี่แม่, cf. Lao ອີ່ແມ່ "I Mae", ) and "I Pho" (อี่พ่อ, cf. Lao ອີ່ພໍ່ "i pho", ), respectively. As Thai only uses cognate prefixes in fairly negative words and expressions, the sound of Isan "i mae" would cause some embarrassment in certain situations. The low status of the language is contributing to the language shift currently taking place among younger Isan people, and some Isan children are unable to speak the language fluently, but the need for Thai will not diminish as it is mandatory for education and career advancement.
Phonological differences.
Isan has maintained the phonological inventory of the Lao language, so any differences in the phonology between Thai and Lao also apply to spoken Isan. Thai and Lao share a similar phonology, being closely related languages, however, several developments occurred in Lao that clearly distinguish them. Tone, including patterns and quality, is the largest contributing factor and varies widely between varieties of Lao or Isan, but together they share splits quite distinct to Standard Thai and other Central Thai speech varieties. There are also several key sound changes that occurred in the Lao language that differentiates it from Thai. As Isan is written according to Thai spelling rules in the Thai script, these changes are not recorded in Isan written in Thai script except for a small number of cases.
Consonantal differences.
Isan noticeably lacks the /r/ of formal Thai, replacing it with /h/ or /l/, as well as /t͡ɕʰ/ which is replaced by /s/. Isan also has the consonant sounds /ɲ/ and /ʋ/ which are absent in Thai. Aside from these differences, the consonantal inventory is mostly shared between the two languages.
C1C2 > C1.
Unlike Thai, the only consonant clusters that traditionally occur is C/w/, limited in Isan and Lao to /kw/ and /kʰw/ but only in certain environments as the /w/ is assimilated into a diphthongization process before the vowels /aː/, /am/, /aːj/ and /a/ thus limiting their occurrence. For example, Isan "kwang" (, "kouang", ) is pronounced *"kuang" (*, *) but "kwaen" as in "kwaen ban" (, "khoèn ban", ), 'to feel at home', has a vowel that does not trigger the diphthongization. The consonant clusters of Proto-Tai had mostly merged in Proto-Southwestern Tai, but clusters were re-introduced with Khmer, Sanskrit, Pali and European loan words, particularly C/l/ and C/r/. Lao simplified the clusters to the first element, but sporadically maintained its orthographic representation as late as the early twentieth century although their pronunciation was simplified much earlier. This was likely an influence of Thai.
In some instances, some loan words are sometimes pronounced with clusters by very erudite speakers in formal contexts or in the speech of Isan youth that is very Thaified, otherwise the simplified pronunciation is more common. Lao speakers, especially erudite speakers may write and pronounce "prôkram" (, ), via French (), and "maitri" (, ) from Sanskrit "maitri" (, ) are common, more often than not, they exist as "pôkam" (, ) and "maiti" (, ), respectively. Similarly, Isan speakers always write and sometimes pronounce, in 'Thai fashion', "maitri" (, ) and "prokraem" (, ), via English 'programme' or 'program' (US), but most speakers reduce it to and , respectively, in normal speech.
/r/ > /h/.
Proto-Southwestern Tai initial voiced alveolar trill /r/ remained /r/ in Thai, although it is sometimes pronounced /l/ in informal environments, whereas Lao changed the sound to the voiceless glottal fricative /h/ in these environments. The sound change likely occurred in the mid-sixteenth century as the Tai Noi orthography after that period has the letter Lao letter " /h/ which was a variant of " /r/ used to record the sound change. Isan speakers employing the Thai script will substitute the Thai letter " /h/, generally only used in loan words, mainly Chinese dialect loan words and more recent European and other borrowings, to record where /h/ appears in place of " /r/. This /h/ is distinct from Lao " /h/ and analogous Thai " /h/ in etymology. The change also included numerous small words of Khmer origin such as "hian" (, , ), 'to learn', which is "rian" (, ) in Thai, from Khmer "riĕn" (, ).
/r/ > /l/.
The shift of Proto-Southwestern Tai */r/ to /h/ in Lao was inconsistent, with some factors that prevented the transition. Instead, these situations led to the shift of /r/ to the alveolar lateral approximant /l/, similar as to what occurs in informal, casual Thai. Polysyllabic loan words from Khmer as well as Indic sources such as Khmer and Pali may have seemed too 'foreign' compared to the monosyllabic loan words which may have been regarded as native, somewhat similar to English 'beef', ultimately from French "boeuf" but fully anglicized in spelling and pronunciation, versus more evidently French loan words such as "crème anglaise", which retains a more French-like pronunciation. Thai speakers sometimes use /l/ in place of /r/ in relaxed, basilectal varieties but this is deprecated in formal speech.
Lao and Thai both have digraphs, or in the case of Lao ligatures, that consist of a silent /h/ that was historically pronounced at some ancient stage of both languages, but now serves as a mark of tone, shifting the sound to a high-class consonant for figuring out tone. The /h/ may have prevented the assimilation of these words to /h/, as these end up as /l/ in Lao. Similarly, this may have also prevented /r/ to /h/ in Khmer loan words where it begins the second syllable.
There are a handful of words where the expected conversion to /h/ did not take place, thus yielding /l/. In some cases, even in the Lao of Laos, this can be seen as historic Siamese influence, but it also may have been conservative retentions of /r/ in some words that resisted this change. For example, Isan has both "hap" (, , ) and "lap" (, , ), both of which mean 'to receive' and are cognates to Thai "rap" (, ), and the "lap" variety in Isan and parts of Laos, especially the south, may be due to Thai contact. In other cases, it is because the words are recent loans from Thai or other languages. In Isan, younger speakers often use /l/ in place of /h/ due to language shift.
/tɕʰ/ > /s/.
Proto-Tai */ɟ/ and */ʑ/ had merged into Proto-Southwestern Tai */ɟ/, which developed into /tɕʰ/ in Thai, represented by the Thai letter ". Only a small handful of Proto-Tai words with */č/ were retained in Proto-Southwestern Tai, represented by the Tai letter ", but this also developed into /tɕʰ/ in Thai and most words with " are either Khmer, Sanskrit or more recent loan words from Chinese dialects, particularly Teochew (Chaoshan Min). Thai also uses the letter " which only occurs in a handful of Sanskrit and Pali loan words where it represented /ɟʱ/, but in Thai has the pronunciation /tɕʰ/. Lao has developed /s/ where Thai has /tɕʰ/, with the letter " /s/, but romanized as 'x', is used to represent cognate words with Thai " or " whereas Thai " is replaced by Lao " /s/ in analogous environments.
Isan speakers will sometimes substitute the Thai letter " /s/ in place of Thai " /tɕʰ/ in cognate words, but this is never done to replace " /tɕʰ/ and sometimes avoided in formal, technical or academic word of Khmer, Sanskrit and Pali origins even if the pronunciation is still /s/, although educated Isan speakers and Isan youth may you use /tɕʰ/ due to code-switching or language shift. Similarly, the letter " /tɕʰ/ is usually retained even if it is better approximated by tone and phonology by " /s/ as is done in similar environments in Lao.
/j/ < /ŋ/ and /j/.
Lao retains a distinction with some words retaining a voiced palatal nasal /ɲ/ from the merger Proto-Southwestern Tai */ɲ/ and */ʰɲ/ and some words with /j/ derived from the merger of Proto-Southwestern Tai */j/ and */ˀj/. The change may have persisted into Thai after the adoption of writing, as some words provide clues to their etymology. For example, Proto-Southwestern Tai */ɲ/ and */ʰɲ/ correspond to the Thai spellings " and " whereas */j/ and */ˀj/ correspond to Thai spellings " and ", respectively, all of which have merged in pronunciation to /j/ in Thai, although as this pronunciation was likely lost shortly after literacy, not all Thai words have this corresponding spelling. Thai also uses the letter " in words of Khmer, Sanskrit and Pali where the source language has /ɲ/ but these words now have /j/ pronunciation.
Lao maintains the distinction with the letters " /ɲ/ and " /j/, but /j/ is a rarer outcome in Lao and most instances of Thai " and " or digraphs " and " will result in Lao " /ɲ/ or " /ɲ/. With a few exceptions, only Proto-Southwestern Tai */ˀj/ yields /j/. Lao, unlike Thai, has also adopted Khmer, Sanskrit and Pali loan words and retains the /ɲ/ pronunciation of the loan source languages, but has also converted the consonantal /j/ into /ɲ/ in borrowings. The Lao letter " also represents /j/, but only in diphthongs and triphthongs as a final element. As the Lao language of Isan is written in Thai according to Thai spelling rules, the phonemic distinction between /j/ into /ɲ/ cannot be made in the orthography, thus Isan speakers write "ya" " which suggests "ya" (, ), 'medicine' but is also used for "[n]ya" (, , ), an honorary prefix used to address a person who is same in age as one's grandparents. These are distinguished in Lao orthography, but Isan speakers either use context or a tone mark, as they differ in tone, to differentiate the words.
/m/ > /l/.
The Proto-Southwestern Tai cluster *"ml" was simplified, producing an expected result of /l/ in Thai and /m/ in Lao. The Saek language, a Northern Tai language distantly related to Thai and Lao preserves these clusters. For instance, Proto-Southwestern Tai *"mlɯn", 'to open the eyes', is "mlong" in Saek (, , ) but appears as "luem" (, ) and "muen" (, "mun", ) in Isan and Lao.
/w/ > /ʋ/.
Lao speakers generally pronounce cognates of Thai with initial /w/ as the voiced labiodental approximant /ʋ/, similar to a faint 'v', enough so that the French chose 'v' to transcribe the Lao letter " /ʋ/. The letter is related to Thai " /w/. The sound /ʋ/ is particularly noticeable in the Vientiane and Central Lao dialects, with a strong pronunciation favored by the élite of Vientiane. In Isan, the rapid but forced resettlement of the people of Vientiane and surrounding areas to the right bank greatly boosted the Lao population, but likely led to some dialect leveling, which may explain the prevalence of /ʋ/ throughout the region, regardless of personal Isan dialect.
The replacement is not universal, especially in Laos, but a shift towards /w/ is also occurring in Isan due to the persistent pressures of the Thai language since the sound /ʋ/ is considered provincial, being different from Thai, as opposed to Laos where it is the prestigious pronunciation. Due to the difference in pronunciation, the French-based system used in Laos uses 'v' whereas the English-based Thai system of romanization uses 'w', so the Lao city of Savannakhét would be rendered 'Sawannakhet' if using the Thai transcription.
/k/ > /t͡ɕ/.
Another influence of the massive migration of the people of Vientiane to the right bank is the common tendency to replace the voiceless velar plosive /k/ with the voiceless alveolo-palatal affricate /t͡ɕ/. For instance, the people of the city of Khon Chaen, more generally referred to as "Khon Kaen" (, "Khon Kèn", ) in formal contexts, refer to their city as "Khon Chaen" (, *, ) in more relaxed settings. In Laos, this is particularly an informal feature specific to Vientiane Lao but is not used in the official written and spoken standard as it is an informal variant, whereas in Isan, it is commonly used but deprecated as a regional mispronunciation. It is also limited to certain words and environments.
Vocalic differences.
C/w/ diphthongization.
Lao innovated a diphthongization that assimilates the /w/ in instances of /kw/ and /kʰw/ in certain environments. This is triggered by the vowels /a/, /aː/, /aːj/ and /am/, but the cluster is retained in all other instances. The /w/ is converted to /uː/ and the vowel is shortened to /ə/. This is not shown in the orthography, as it must have evolved after the adoption of writing in the fourteenth century. Cognate words in Lao or Isan where this diphthongization occurs have no alteration in spelling from Thai counterparts. For example, the Thai word for 'to sweep' is "kwat" (, ) but is "kwat" (, "kouat", ) and has the suggested pronunciation but is pronounced *"kuat" (*, * "kouat"). The counterpart of Thai "khwaen" (, ), 'to hang' (something) is also "khwaen" (, "khwèn", ) since the vowel /ɛː/ does not trigger diphthongization.
The vowels /a/, /aː/, /aːj/ and /am/ correspond to Thai ", ", " and " and the Lao ", ", " and ". The clusters that can undergo this transformation are /kw/, Thai " and Lao " or /kw/, Thai " and ' and Lao " and ". The non-diphthongized pronunciations as used in Thai are also used by some Isan speakers as a result of Thai influence. In Laos, non-diphthongization is not incorrect, but may sound like a Thai-influenced hypercorrection or very pedantic. As it is the normal pronunciation in Laos and Isan, it limits the instances of consonant clusters that are permissible.
/ua/ > /uːə/.
The Thai diphthongs and triphthongs with the component /ua/ undergo a lengthening of the /u/ to /uː/ and shortens the /a/ to /ə/, although the shortened diphthong can sound like /uː/ to Thai speakers. In Thai, this includes the vowels /ua/ represented medially by " and finally by ", /uaʔ/ by " and the final triphthong /uaj/ by ". Lao has /uːə/ represented medially by " and finally by ", /uːəʔ/ by " and the final triphthong /uːəj/ by ".
For example, the Thai word "tua" (, , used as the classifier for animals, letters as well as general word to mean 'creature' is instead "tua" (, , ) in Isan. To Thai speakers who may not perceive the weak schwa /ə/ may hear "tu" (, ), an archaic first-person pronoun no longer used or used in a pejorative fashion. This may have been another innovation, like C/w/ diphthongization, that occurred after the adoption of writing as it is not represented orthographically.
/ɯ/ > /ɨ/.
The close back unrounded vowel /ɯ/ is centralized to the close central unrounded vowel /ɨ/ in Lao which is not found in Thai. This also applies to all variants of /ɯ/ that occur in Thai, i.e., all cognates with instances of Thai /ɯ/ are Lao /ɨ/, including diphthongs and tripthongs that feature this vowel element. Some very traditional dialects of Southern Lao and the Phuan dialect front the vowel all the way to /iː/.
/ɤ/ > /ɘ/.
The close-mid back unrounded vowel /ɤ/ is centralized to the close-mid central unrounded vowel /ɘ/ in Lao. Similar to the conversion of /ɯ/ to /ɨ/, it also affects all instances in diphthongs as well.
Epenthetic vowels.
Abugida scripts traditionally do not notate all vowels, especially the short vowel /a/, usually realized as /aʔ/ in Thai and Lao phonology. This especially affects the polysyllabic loan words of Sanskrit, Pali or Khmer derivation. Instances of when or when not to pronounce a vowel have to be learned individually as the presence of the vowel is inconsistent. For example, the Sanskrit word "dharma" (, ) which can mean 'dharma', 'moral' or 'justice', was borrowed into Thai as simply "tham" ( ). As a root, it appears as simply "tham" as in "thamkaset" ( ) 'land of justice' or 'righteous land' with the /aʔ/ or "thammanit" ( ), 'moral person' with /aʔ/. This is not always justified by etymology, as the terms derive from Sanskrit "dharmakṣetra" (, )—actually signifies 'pious man' in Sanskrit—and "dharmanitya" (, ), respectively, both of which feature a pronounced but unwritten /a/. Lao and most Isan speakers in relaxed environments will pronouce the 'extra' vowel yielding *"thammakaset" (, "thammakasét", ) and "thammanit" (, , ). There are also instances where Thai has the epenthetic vowel lost in Lao, such as "krommathan" (, ), 'debt contract', whereas Lao has nativized the pronunciation to "kromtham" (, "kômtham", ). This is an exception, as the extra vowel is a sign of Lao-retained pronunciation such as Thai "chit" (, ), 'paiting' from Sanskrit "citra" (, ) which is "chit" (, , ), "chit"["ta"] (, "chitta", ) or extremely epentheticized "chit"["tara"] (, "chittala", in Isan.
Although it may seem like a minor difference, it is akin to the stigmatized mispronunciations of the English words 'athlete' () and 'arthritis' (, US ) as *'athelete' (*) or *'arthuritis' (*, US ), respectively. As another feature of Isan that deviates from Thai, it is deprecated. Few Isan people are aware that the stigmatized pronunciations are actually the 'proper' Isan form inherited from Lao. Many of these loan words are limited to academic and formal contexts which usually trigger code-switching to formal Thai, thus Isan speakers may pronounce these words more akin to Thai fashion although to varying degrees of adaptation to Isan pronunciation. Lao speakers also tend to insert epenthetic vowels in normal speech, as opposed to standard Thai where this is less common, thus 'softening' the sentence and making dialogue-less staccato. For instance, the Isan phrase "chak noi" (, ) which means 'in just a bit' is often pronounced "chak-ka noy" (*จักกะน้อย , cf. Lao *ຈັກກະນ້ອຍ) but this may be perceived as 'slurred' speech to Thai speakers.
Retention of certain historical Lao pronunciations.
'Mekong River'
'Chaiburi' (Thai name of the Lao province of Xaignabouli)
'Hanuman'
Tones.
Even Thai words with clear cognates in Lao and Isan can differ remarkably by tone. Determining the tone of a word by spelling is complicated. Every consonant falls into a category of high, middle or low class. Then, one must determine whether the syllable has a long or a short syllable and whether it ends in a sonorant or plosive consonant and, if there are any, whatever tone marks may move the tone. Thai กา "ka", crow, has a middle tone in Thai, as it contains a mid-class consonant with a long vowel that does not end in a plosive. In Standard Lao, the same environments produce a low-rising tone but is typically or rising-mid-falling in Western Lao.
Despite the differences in pattern, the orthography used to write words is nearly the same in Thai and Lao, even using the same tone marks in most places, so it is knowing the spoken language and how it maps out to the rules of the written language that determine the tone. However, as the Tai languages are tonal languages, with tone being an important phonemic feature, spoken Lao or Isan words out of context, even if they are cognate, may sound closer to Thai words of different meaning. Thai คา "kha" , 'to stick' is cognate to Isan คา and Lao ຄາ, which in Vientiane Lao is pronounced , which may sound like Thai ค้า "kha" , 'to trade' due to similarity in tone. The same word in some parts of Isan near Roi Et Province would confusingly sound to Thai ears like ขา "kha" with a rising tone, where the local tone patterns would have many pronounce the word with a rising-high-falling heavier on the rising. Although a native Thai speaker would be able to pick up the meaning of the similar words of Isan through context, and after a period of time, would get used to the different tones (with most Lao and Isan speech varieties having an additional one or two tones to the five of Thai), it can cause many initial misunderstandings.
Different speaking styles.
Despite the similarities, the Thai and Lao languages have very different speaking styles. Thai speakers tend to use many euphemisms, cute expressions, wordplay or abbreviations and situations that require 'nuanced' usage or implied meanings. For instance, in relaxed and casual speech, pronouns are normally dropped unless needed for emphasis or disambiguation. With Bangkok serving as Thailand's primary city and home to the majority of media corporations, government, academic, entertainment and infrastructure as well as roughly a quarter of the population in its metropolitan area, the influence of Bangkok's urban slang permeates spoken language of most native Thai speakers.
Lao conversations are often more direct. Although spoken Isan has its own set of flowery language, wordplay and strategic vocabulary, they are not as commonly invoked in speech but rather feature heavily in the lyrics of local musical forms such as "molam" and poetry. Lao speakers also tend to use most pronouns, especially the ones for 'I' and 'you' even in relaxed speech. In Thai and Lao, the increased usage of pronouns occurs in formal and polite usage whereas both reduce their usage in relaxed, casual speech. Thus, compared to Thai, Isan conversations can seem more abrupt, serious, formal to the point of distant to Thai speakers. This perception is offset by the large number of Isan words that sound like or are cognate to Thai words that are considered vulgar, and the greater use of native Tai vocabulary which may seem simple compared to the generally larger proportion of Indic vocabulary in Thai.
Lexical differences from Thai.
Although the majority of Isan words are cognate with Thai, and Thai influences are even creeping into the vocabulary, many basic words used in everyday conversation are either lacking cognates in Thai, but share them with Lao. Some usages vary only by frequency or register. For instance, the Thai question word 'เท่าไหร่' is cognate with Isan 'เท่าใด' and Lao 'ເທົ່າໃດ' , but Isan and Lao tend to use a related variant form 'ท่อใด' and 'ທໍ່ໃດ' , respectively, more frequently, although the usage is interchangeable and preference probably more related to region and person.
In other areas, Isan preserves the older Tai vocabulary. For example, the old Thai word for a 'glass', such as a 'glass of beer' or 'glass of water' was 'จอก' "chok" , but this usage is now obsolete as the word has been replaced by Thai 'แก้ว' "kaew" . Conversely, Isan and Lao continue to use 'จอก' and 'ຈອກ' "chok" to mean 'glass' (of water) as , but Isan 'แก้ว' and Lao 'ແກ້ວ' "kéo" retain the earlier meaning of Thai 'แก้ว' as 'gem', 'crystal' or 'glass' (material) still seen in the names of old temples, such as 'Wat Phra Kaew' or 'Temple of the Holy Gem'. Nonetheless, a lot of cognate vocabulary is pronounced differently in vowel quality and tone and sometimes consonant sounds to be unrecognizable or do not share a cognate at all. For example, Isan บ่ "bo" and Lao ບໍ່ "bo" are not related to Thai ไม่ , "mai"
Overview of the relationship with standard Lao.
Whereas Thai and Isan are mutually intelligible with some difficulty, there are enough distinctions between the two to clearly separate the Thai and Isan languages based on vocabulary, grammar and pronunciation differences, with even Isan written in Thai recognizable as Isan due to the preponderance of Lao words with no equivalent Thai cognate or have come to mean different things. Isan houses the majority of Lao speakers and the affinity of shared culture with Laos is palpable in the food, architecture, music and language of the region. In its purest spoken form, the Isan language is basically the same as what is spoken in Laos.
Using just tone and some lexical items, there are at least twelve distinct speech varieties of Isan, most of which also continue across the Mekong River into Laos. In fact, the different speech varieties on roughly the same latitude tend to have more affinity with each other, despite the international border, than to speech varieties to the north and south. Only a handful of lexical items and grammatical differences exist that differentiate Isan as a whole, mainly as a result of more than a century of political separation, but most of these terms were introduced in the 1980s when the region was better integrated into Thailand's transportation and communication infrastructure.
Spelling and orthography.
Isan and Lao have drifted away from each other mostly in terms of the written language. The Isan people were forced to abandon their traditional Tai Noi script and have come to use the Thai written language, or Isan written in Thai, for communication. In Laos, Tai Noi was modified into the modern Lao script, but several spelling changes in the language during the transition from the Lao monarchy to the communist rule moved Thai spelling and Lao spelling of cognate words further apart. Isan, writes all words with Thai cognates as they exist in Thai, with clusters, special letters only found in obscure Sanskrit words and etymological principles that preserve silent letters and numerous exceptions to Thai pronunciation rules although a small handful of Isan words, with no known or very obscure Thai cognates, are spelled more or less the same as they are in Lao.
Lao spelling in Laos was standardized in the opposite direction. Whilst previously written in a mixture of etymological and phonetical spellings, depending on the audience or author, the language underwent several reforms that moved the language towards a purely phonetical spelling. During the restoration of the king of Louang Phabang as King of Laos under the last years of French rule in Laos, the government standardized the spelling of the Lao language, with movement towards a phonetical spelling with preservation of a semi-etymological spelling for Pali, Sanskrit and French loan words and the addition of archaic letters for words of Pali and Sanskrit origin concerning Indic culture and Buddhism.
Spelling reforms under the communist rule of Laos in 1975 were more radical, with the complete abolition of semi-etymological spelling in favor of phonetical spelling, with the removal of silent letters, removal of special letters for Indic loan words, all vowels being written out implicitly and even the elimination or replacement of the letter 'ຣ' (but usually pronounced /l/) in official publications, although older people and many in the Lao diaspora continue to use some of the older spelling conventions. The examples demonstrate the differences between Lao and Isan, using Thai orthography, but also that between archaic and modern Lao, as well as the general pronunciation and spelling practices between Standard Thai and Standard Lao in general.
Silent letters: Lao removal and Thai retention.
Numerous loan words from other languages, particularly Sanskrit and Pali, have numerous silent letters, sometimes even syllables, that are not pronounced in either Thai, Isan or Lao. In most cases, one of the final consonants in a word, or elsewhere in more recent loans from European languages, will have a special mark written over it (Thai ' ໌ '/Lao ' ໌ ' known in Isan as "karan" (การันต์) and Lao as "karan"/"kalan" (ກາລັນ/archaic ກາຣັນຕ໌ ).
In reforms of the Lao language, these silent letters were removed from official spelling, moving the spelling of numerous loan words from etymological to phonetical. For instance, the homophones pronounced are all written in modern Lao as ຈັນ CH-A-N, "chan", but these were previously distinguished in writing as ຈັນທ໌ CH-A-N-[TH] or ຈັນທຣ໌ CH-A-N-[TH]-[R], 'moon'; ຈັນທ໌ CH-A-N-[TH] or ຈັນທນ໌ CH-A-N-[TH]-[N], 'sandalwood' and ຈັນ CH-A-N, 'cruel.' In Isan, using Thai etymological spelling, the respective spellings are จันทร์ CH-A-N-[TH]-[R], จันทน์ CH-A-N-[TH]-[N] and จัน, CH-A-N, with the latter being a shared Lao-Isan word with no Thai cognate.
'Vientiane'
'gear'
'animal'
Consonant clusters: Lao removal and Thai retention.
The oldest texts in the Tai Noi corpus show that the earliest stages of the Lao language had consonant clusters in some native words as well as many loan words from Khmer, Mon, other Austroasiatic languages, Sanskrit and Pali. Although most of these were maintained in Thai pronunciation, these clusters were quickly abandoned, indicating that the Tai dialects that became the Lao language lacked them or that they lost them through separate language development. Unlike the Thai script, Lao preserves a subscript version of /l/ and /r/ ' ຼ ' that was commonly used in the ancient Tai Noi script when these clusters were pronounced and written.
Some consonant clusters were maintained in the Lao language for some vocabulary, mostly of Sanskrit and Pali derivation and used in royalty or religious settings, but the most recent spelling reforms in the Lao language removed most of them. The Thai language has preserved all of them, and when Isan is written in Thai, cognates of Thai words are spelled as if they are pronounced in Thai, with consonant clusters that are usually not pronounced in Isan except some religious and technical terms.
'garlic'
'country'
'to be entertained'
'to be finished'
'Buddha'
Explicit gemination in Lao.
As consonants may have one value at the start of a consonant and one at the end, occasionally the same letter will be used to end one syllable and begin the next. This remains common in many loan words from Sanskrit and Pali, and was once the case in Lao orthography, but now the different consonant sounds are written out explicitly and no longer implied from older and confusing rules of spelling. Thai, with its etymological spelling, preserves the implied pronunciation of these geminated consonant groupings.
'girl of noble birth'
'good fortune'
'wife' (formal)
Lao retention of Tai Noi vowel symbols.
Lao uses two vowel symbols inherited from Tai Noi, one of which ' ໍ ' or the "nikkhahit" (ນິກຄະຫິດ ) is used to denote the vowel in open syllables where that is the final sound in the syllable and the other ' ົ ' or "mai kan" (ໄມ້ກົງ ) which is used to denote the vowel , both of which are sometimes implied in Thai orthography. The latter symbol is also used with some vowels with various meanings. The "viram" (Archaic ວິຣາມ/ວິລາມ ) was formerly used as a variant of Lao letter 'ຍ' in a word as well as several other uses.
'person' or 'people'
'litter' or 'palanquin'
'emerald'
'small'
'to write'
'green'
Lao simplification of terminal consonants.
Both Thai, Lao and Isan only permit the final consonants , , , , , and , with many letters beginning a syllable with one sound and ending a syllable or word with another. Spelling reforms in Laos restricted the final consonants to be spelled 'ກ', 'ງ', 'ດ', 'ນ', 'ບ' and 'ມ' which correspond to Thai letters 'ก', 'ง', 'ด', 'น', 'บ' and 'ม', respectively. As Thai has retained these final consonants according to etymology, this has further moved Lao spelling from Thai and Isan written in Thai in a large number of common words.
'to draw a picture'
'happiness'
'ancient times'
Lao vowel reduction.
The archaic vowels 'xັຽ' and 'xັມ' were replaced with existing vowels 'ໄ' and 'ຳ' as these pairs both represented and , respectively. The Lao vowel 'ໄxຽ' was also replaced by 'ໄ'.
'to update'
'dharma'
'disciplined' or 'educated person'
Lao explicit vowels.
In the abugida systems, open syllables are assumed to have or following them. Modern Lao spelling requires that all vowels are written out, altering the spelling of numerous words and furthering the language from Thai. As this can alter the tone of the words, sometimes tone marks or silent are used to either represent the actual pronunciation of the word or restore it to its original pronunciation.
'city'
'street'
'paradise'
'vowel'
Lao ligatures.
Lao uses a silent letter 'ຫ' in front of consonants 'ງ' , 'ຍ' , 'ນ' , 'ມ' , 'ລ' , 'ຣ' or and 'ວ' to move these consonants into the high tone class, used to alter the tone of a word. This is analogous to the use of 'ห' before the equivalent 'ง' , 'ย' (but in Isan, sometimes represents and also 'ญ', which is in Thai and represents in Isan), 'น' , 'ม' , 'ล' , 'ร' (generally when in a digraph in Isan) and 'ว' (generally in Isan.
As a legacy of the Tai Noi script, Lao writers can use the special ligature 'ໜ' HN instead or, when typesetting or rendering unavailable, it can be optionally be written 'ຫນ' H-N as well as 'ໝ' HM and modern alternative 'ຫມ'. Both 'ຫລ' H-L and 'ຫຣ' H-R have the same ligature form 'ຫຼ' HL/R. Previous versions of the script also had special ligatures 'ພຽ' PHY ('ພ' + 'ຍ' ) and 'ຫຽ' HY ('ຫ' + 'ຍ' ) with the latter replaced by 'ຫຍ' HY (high class tone). Former ligatures such as SN and ML have disappeared or were split into syllables as consonant clusters were generally lost or replaced. For example, Archaic Lao ສນອງ SN-O-NG and ມຼາບຼີ ML-A-BR-I have become in the modern language ສະໜອງ S-A-N-O-NG "sanong" , 'message' (derived from Khmer "snaang" ស្នង ) and ມະລາບີ M-A-L-A-B-I "malabi" , approximation of endonym of the Mlabri people. Thai preserves writing the consonants together, although in the modern Thai language these consonants are separated by a vowel according to the current pronunciation rules.
Both Tai Noi and the current Lao alphabet lack equivalents to the Thai vowel ligatures 'ฤ', 'ฤๅ', 'ฦ' 'ฦๅ' and are mainly used to represent the sounds or , , and , respectively, although the latter two symbols are obsolete in modern Thai. These symbols were used to represent loanwords from Sanskrit 'ऋ' , 'ॠ' , 'ऌ' and 'ॡ' , respectively, but these are relatively rare sounds in Sanskrit.
'Louang Phrabang'
'mouse' 
'fruit'
'season'
'hermit'
'mysterious'
'famous'
Typographical differences.
Traditionally, no punctuation exists in either Thai or Lao, with spaces used to separate lists, sentences and clauses, but otherwise words are written with no spaces between them. A few symbols include the cancellation mark 'x໌' used to mark letters in loan words that are not pronounced, the repetition symbol 'ໆ' used to indicate words or phrases are to be repeated, an ellipsis-like symbol 'ຯ' used to shorten lengthy phrases, such as royal titles or to indicate that following portions have been removed and the equivalent to the "et cetera" symbol 'ຯລຯ'. These all have equivalents in the Thai script as 'x์', 'ๆ', 'ฯ' and 'ฯลฯ'.
Other Thai symbols, such as '๏', used for marking the beginning of texts, lines or stanzas, '๛' to mark the end of chapters, 'ฯะ' to mark the end of stanzas and '๚' to mark the end of sections. These symbols could be combined to provide meaning. A similar system was in use in Laos but was later abolished. The system is mostly archaic in Thai texts, but is still taught as many old texts feature these symbols.
Lao only uses two of the tone marks 'x່' and 'x້', although 'x໊' and 'x໋' may occasionally be used to record idiosyncratic or emotional speech, as aids to capture tones of different dialects or onomatopoeia. In Thai, the equivalent tone marks are 'x่', 'x้', x๊ and x๋, respectively. Although in Thai, the third and fourth tone markers are rare, they are frequently used to approximate the tones of hundreds of Chinese (mainly Teochew, Hokkien and Hainanese) loan words, dialectal expressions and onomatopoeia.
'soy sauce'
'Chinese noodle soup'
In modern writing, Thai and Lao have both adopted the question mark "?", exclamation point "!", comma "", parentheses "()", hyphen "-", ellipsis "...", and period "." from their respective English and French sources. Since Isan adopted the Thai punctuation via English, the quotation marks "" are used instead of guillemets, "«»", and spaces are not inserted before terminal punctuation marks. Although Lao speakers in Laos will often use French-style punctuation, English-style punctuation is increasingly becoming more commonplace there.
Grammatical differences.
Formal language.
Since the use of Central Thai is deemed polite and mandatory in official and formal settings, Isan speakers will often use the Thai ครับ, "khrap" (), used by males, and ค่ะ, "kha" (), used by females, sometimes in place of or after the ones shared with Lao. Isan speakers, however, do not use the very formal particle ข้าน้อย, "khanoy" (, cf. Lao: ຂ້ານ້ອຍ/archaic ຂ້ານ້ຽ) at the end of sentences. Also, the use of เจ้า, "chao" (, cf. Lao: ເຈົ້າ) and formal โดย, "doy" (, cf. Lao: ໂດຍ/archaic ໂດຽ, "dôy"), to mark the affirmative or "yes" is no longer used in Isan, instead this is replaced with the general ending particles or the equivalent Thai expression.
Word order.
A very few compounds in Lao are left-branching, but most of the time they are right-branching, as they are almost always in Thai and Isan.
Lexical comparison with Lao.
Lao and Isan share most of their vocabulary, tone, and grammatical features, and the barriers of comprehension that would exist between a Thai speaker and a Lao speaker are absent between speakers of Isan and Lao. Technical, academic, and scientific language, and different sources for loan words have diverged the speech to an extent. Isan has borrowed most of its vocabulary from Thai, including numerous English and Chinese (Min Nan) loan words that are commonly used in Thai. Lao, on the other hand, has influences from French and Vietnamese that come from the establishment of the Protectorate of Laos and its inclusion in French Indochina. In ordinary and casual speech, only a few lexical items separate Isan and Lao, and many dialects do not end at the border.
Thai influences.
The main thing that differentiates Isan from Lao is the use of numerous Thai words. The process accelerated with greater integration of Isan into Thai political control in the early 20th century. Thai words make up the bulk of scientific, technical, governmental, political, academic, and slang vocabularies that have been adopted in Isan. Many words used in Isan have become obsolete, such as the use of ขัว, "khua" () and น้ำก้อน, "nam kon" (), which exist in Laos as ຂົວ and ນ້ຳກ້ອນ, but replaced by Thai forms สะพาน, "saphan", and น้ำแข็ง, "nam khaeng", respectively. Thai, Isan, and Lao share vocabulary, but sometimes this can vary in frequency. For instance, Lao speakers use ສະພານ, "saphan", as a more formal word for "bridge". The very formal Thai word for "house", เรือน, "reuan" () is cognate to the common Isan เฮือน, "heuan", and Lao ເຮືອນ, "huan" (). Although many Lao speakers can understand and speak Thai due to exposure to Thai publications and media, the official status of the language in Laos, pressure to preserve the Lao language, and unique neologisms and other influences differentiate the language from Thai. A few neologisms in Laos are unique coinages.
Lack of French influences.
After the division of the Lao-speaking world in 1893, French would serve as the administrative language of the French Protectorate of Laos, carved from the Lao lands of the left bank, for sixty years until 1953 when Laos achieved full independence. The close relationship of the Lao monarchy with France continued the promotion and spread of French until the end of the Laotian Civil War when the monarchy was removed and the privileged position of French began its decline. Many of the initial borrowings for terms from Western culture were imported via French, as opposed to Isan which derived them from English via Thai. For instance, Isan speakers use "sentimet" ( ) in approximation of English 'centimeter' () whereas Lao uses "xangtimèt" ( ) in approximation of French "centimètre" (). Lao people also tend to use French forms of geographic place names, thus the Republic of Guinea is "kini" ( ) via Thai based on English 'Guinea' () as opposed to "kiné" ( ) from French "Guinée" ().
Laos maintains the French-language weekly "Le Rénovateur", but French-language content is sometimes seen alongside English in publications in older issues of "Khaosane Phathét Lao News" and sporadically on television ad radio. French still appears on signage, is the language of major civil engineering projects and is the language of the élite, especially the older generations that received secondary and tertiary education in French-medium schools or studied in France. France maintains a large Lao diaspora and some of the very well-to-do still send their children to France for study. The result of this long-standing French influence is the use of hundreds of loan words of French origin in the Lao language of Laos—although many are old-fashioned and somewhat obsolete or co-exist alongside more predominate native usages—that are unfamiliar to most Isan speakers since the incorporation of the right bank into Siam prevented French influence.
Lack of Vietnamese Influences.
Because of the depopulation of the left bank to Siam prior to French colonization, the French who were already active in Vietnam brought Vietnamese to boost the population of the cities and help administer the region. Many Lao that received a French-language education during the period of French Indochina were educated in French-language schools in Vietnam, exposing them to French and Vietnamese languages and cultures. As the Vietnamese communists supported the "Pathét Lao" forces, supplying Lao communist militia with weaponry and training during the two-decade-long Laotian Civil War, large numbers of Vietnamese troops have been stationed at various times in Laos' post-independence history, although the Vietnamese military presence began to wane in the late 1980s as Laos pursued closer relations with its other neighbors and entered the market economy.
As a result of Vietnamese immigration and influence, a handful of lexical items have been borrowed directly from Vietnamese, most of which are not used in Isan, although 'to work' or "wiak" ( ) has spread into Isan from Lao "viak" () from Vietnamese "việc" (). Vietnamese Laotians comprise roughly 79,000 people in Laos today, roughly three times the number of Vietnamese people in Isan, and operate local schools and community associations in the major cities, although many of the Vietnamese Isan people are descendants of Vietnamese that fled Laos during the Laotian Civil War and many of their descendants have assimilated to the local language. The Vietnamese have little cultural impact in Isan, and thus aside from "wiak", most Vietnamese terms borrowed in Lao are not used in Isan. The opening of Laos in the 1990s has significantly reduced the presence of the Vietnamese military and technical assistance.