Serbians

The term Serbians in English language is a polysemic word, with two distinctive meanings, derived from morphological differences:
Morphology 1: Serb-ian-s, derived from the noun "Serb" and designating ethnic Serbs, thus having a synonymous ethnonymic use.
Morphology 2: Serbia-an-s, a demonym derived from the noun "Serbia", designating the population of Serbia, in general.
In English language, the use of term "Serbians" depends on the context, with demonymic use being more common, but not exclusive.
Demonymic use.
The term "Serbians" is used in English language as a demonym for all citizens of Serbia, regardless of their ethnic, linguistic, religious or other cultural distinctions. In Serbian, however, the term "Srbijanci" () is also used for ethnic Serbs from Serbia, or in a narrower sense, Serbs from Central Serbia (Serbia proper). The term thus excludes ethnic Serbs in the neighboring countries, such as Bosnia and Herzegovina, Croatia, Montenegro and North Macedonia, for which the common term "Srbin" () is used. In English, the two are commonly used interchangeably, with the term "Serbians" sometimes applied to ethnic Serbs outside Serbia (such as "Bosnian Serbians" for Bosnian Serbs). Likewise, the term "Serbs" has been erroneously applied to all citizens of Serbia regardless of their ethnicity.
The term and usage of "Srbijanci" is controversial in Serbian-speaking areas. In Croatian usage, "Srbijanci" are all citizens of Serbia regardless of ethnicity, while "Srbi" is the term for ethnic Serbs, including Serbs of Croatia. The term itself is mostly used in Croatia and province of Vojvodina. It has been noted that this type of demonym and distinction between ethnicity and nationality are only found in Bosnia and Herzegovina and Serbia as opposed to other European countries, even other former Yugoslav republics.
In the 1852 "Serbian Dictionary", the entry includes the following: 
A popular Serbian folk song contains a chorus " ..."jelek" (vest), "anterija" (short vest), and "opanci" (traditional moccasins), is how you recognize a "Srbijanac" (Serbian)...", describing the Serbian folk costume.
Variant terms like "Old Serbians" () and "Southern Serbians" () were used as designations for populations from historical regions of Old Serbia, and Vardar Macedonia respectively.