An abbreviation (from Latin , meaning short) is a shortened form of a word or phrase, by any method. It may consist of a group of letters or words taken from the full version of the word or phrase; for example, the word abbreviation can itself be represented by the abbreviation abbr., abbrv., or abbrev.; NPO, for nil (or nothing) per (by) os (mouth) is an abbreviated medical instruction. It may also consist of initials only, a mixture of initials and words, or words or letters representing words in another language (for example, e.g., i.e. or RSVP). Some types of abbreviations are acronyms (some pronounceable, some initialisms) or grammatical contractions or crasis. An abbreviation is a shortening by any of these or other methods. Types Acronyms, initialisms, contractions and crasis share some semantic and phonetic functions, and all four are connected by the term "abbreviation" in loose parlance. An initialism is an abbreviation pronounced by spelling out each letter, i.e. FBI (), USA (), IBM (), BBC () A contraction is a reduction in the length of a word or phrase made by omitting certain of its letters or syllables. Consequently, contractions are a subset of abbreviations. Often, but not always, the contraction includes the first and last letters or elements. Examples of contractions are "li'l" (for "little"), "I'm" (for "I am"), and "he'd've" (for "he would have"). History Abbreviations have a long history. They were created to avoid spelling out whole words. This might be done to save time and space (given that many inscriptions were carved in stone) and also to provide secrecy. In both Greece and Rome the reduction of words to single letters was common. In Roman inscriptions, "Words were commonly abbreviated by using the initial letter or letters of words, and most inscriptions have at least one abbreviation". However, "some could have more than one meaning, depending on their context. (For example, can be an abbreviation for many words, such as , , , , , , and .)" Many frequent abbreviations consisted of more than one letter: for example COS for consul and COSS for its nominative etc. plural consules. Abbreviations were frequently used in English from its earliest days. Manuscripts of copies of the Old English poem Beowulf used many abbreviations, for example the Tironian et () or for and, and for since, so that "not much space is wasted". The standardisation of