Bulgarian is a complex language with many grammatical categories. Its morphology is rich, and its vocabulary includes both classical and folk loanwords. Its parts of speech – nouns, adjectives, numerals, verbs and pronouns – vary grammatically depending on their use. Mutable parts of speech are those that vary based on usage, while immutable words do not. Pronouns are the only group of mutable parts that retain case inflections.

The Bulgarian language combines elements of several Slavic languages, including Old Bulgarian and Eastern Slavonic. It has a number of unique features that make it distinctive among other Slavic languages. Bulgarian is also one of the few Slavic languages to have a fourth mood, in addition to the indicative, imperative and subjunctive moods shared by most European languages. This is the inferential (preizkazno) mood, which is used to describe unwitnessed events.

Another distinct feature of Bulgarian is the use of abstract particles to strengthen a statement. These are usually placed at the end of questions or commands, and they can express a variety of feelings and emotions, from indignation to annoyance and even irritation. Examples of such particles include kazhi mi, be – tell me; taka li, be? – is that so?; vyarno li, be? – don’t say it; and, oh cynic, be careful.

Besides the Bulgarian language’s own lexical wealth, it contains a large number of borrowed words from the classical languages Latin and Greek, mainly through Romanian and Aromanian. These words are used mostly in international terminology, but some of them have acquired Bulgarian meanings. Other words have come to Bulgarian through Ottoman Turkish, or more recently through English.

In addition, Bulgarian has a large number of loanwords from other Turkic languages, and a few words have come to the country from other countries. Bulgarian is also influenced by the Romance languages and to some extent, by Eastern Slavonic.

The Bulgarian language has a very complex system of declension, which makes it difficult to learn. In particular, the definite articles must agree in gender and case with the noun they are attached to. Mastering this morphology is essential to speaking the Bulgarian language fluently.

In addition, Bulgarian has a number of adverbs and prepositions that are specific to the language and are not found in other Slavic languages. These are useful if you want to communicate more precisely. They can help you avoid ambiguity when explaining concepts to foreigners. They can also save you time and effort when preparing texts in Bulgarian.