Bulgarian /bʌlˈɡɛəriən/, /bʊlˈ-/ (български език, pronounced [ˈbɤɫɡɐrski ɛˈzik]) is an Indo-European language, a member of the Southern branch of the Slavic language family. It is the language of the Bulgarians.

Bulgarian, along with the closely related Macedonian language (collectively forming the East South Slavic languages), has several characteristics that set it apart from all other Slavic languages: changes include the elimination of case declension, the development of a suffixed definite article (see Balkan language area), and the lack of a verb infinitive, but it retains and has further developed the Proto-Slavic verb system. Various evidential verb forms exist to express unwitnessed, retold, and doubtful action.