In English language, the use of term Serbians depends on the context, with demonymic use being more common, but not exclusive.
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 (Serbian: / 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 (pl. Srbi) 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[dubious ] 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.[a]
In the 1852 Serbian Dictionary, the entry includes the following:
Srbijanac - ?ovek iz Srbije (man from Serbia); Srbijanski - koji je iz Srbije (which is from Serbia)
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 (Serbian: / Starosrbijanci) and Southern Serbians (Serbian: / Ju?nosrbijanci) were used as designations for populations from historical regions of Old Serbia, and Vardar Macedonia respectively.
Ovim nije kraj na?ih podela. Pored re? «do?o?i», postoji i pojam «pre?ani» i «Srbijanci». A kako se zovu Hrvati iz Bosne? Hrvatijanci? Ne, ta re? je naravno moja, ve?ta?ka, izmi?ljena. Ali, zasto[ ta pojava postoji samo kod Srba? Srbi i Srbijanci. Austrougarska je izmislila te podele, a mi Srbi smo ih prihvatili. U tome je problem. Mi prihvatamo jezik neprijatelja. Tu?e olako uzimamo, a odri?emo se svoga. Tako smo olako odbacili i ?irilicu.
O upotrebi pojma ,,Srbijanac" [...] Me?utim, unutar dana?njih granica Srbije, ,,Srbijanci" se uglavnom koriste na severu, kako bi se (uglavnom pe?orativno i prezrivo) denotirali ,,ged?ovani", primitivci i sirotinja sa juga koja odudara od ,,zapadnoevropskih" manira, obi?aja i ,,kulture" tzv. ,,Vojvo?ana". O?igledno je da ova upotreba, me?utim, nastaje kasnije i nema veze sa onim ,,Srbijancima" o kojima svedo?e Vuk Karad?i? i Branko Radi?evi?.
The dictionary definition of Serbians at Wiktionary