Although the Brčko District is formally held in condominium by both entities, it is a de facto third entity, as it has all the same powers as the other two entities and is under the direct sovereignty of BiH.
The Constitution of Republika Srpska avoids naming the languages, instead listing them as "the language of the Serb people, the language of the Bosniak people and the language of the Croat people" (because there is no consensus whether this is the same language or three different languages).
Including refugees abroad
Excluding Republika Srpska's 48% of the Brčko District

Republika Srpska (Serbian Cyrillic: Република Српскa, pronounced [repǔblika srpska]) is one of two constitutional and legal entities of Bosnia and Herzegovina, the other being the Federation of Bosnia and Herzegovina. The entities are largely autonomous. The administrative centre is Banja Luka.

In Serbo-Croatian, Republika Srpska means "Serb Republic". The second word is a nominalized adjective derived by adding the suffix -ska to srb-, the root of the noun Srbin, meaning Serb. The -ps- sequence rather than -bs- is a result of voicing assimilation. Although the name Republika Srpska is sometimes glossed as Serb Republic or Bosnian Serb Republic, and the government of Republika Srpska uses the semi-Anglicized term Republic of Srpska in English translations of official documents, western news sources such as the BBC,The New York Times, and The Guardian generally refer to the entity as the Republika Srpska.

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Wikipedia