Bulgarian nouns have the grammatical categories gender, number, case (only vocative) and definiteness.
A noun has one of three specific grammatical genders (masculine, feminine, neuter) and two numbers (singular and plural). The plural is formed by adding to or replacing the singular ending.
го̀ст - го̀сти (guests)
дърво - дърва (trees)
With cardinal numbers and some adverbs, masculine nouns use a separate numerical plural form. It is a remnant of the grammatical dual number, which disappeared from the language in the Middle Ages. The numerical form is used in the masculine whenever there is a precise amount of something, regardless of the actual number.
In modern Bulgarian, definiteness is expressed by a definite article which is post-fixed to the noun, much like in the Scandinavian languages or Romanian, or to the first nominal constituent of a definite noun phrases:
There are four singular definite articles. Again, the choice between them is largely determined by the noun's ending in the singular.
A Bulgarian adjective agrees in gender, number and definiteness with the noun it is appended to and is put usually used in front of the noun.
хубав ресторант - nice restaurant (masculine)
хубава градина - nice garden (feminine)
хубаво село - nice village (neuter)
The comparative and the superlative form are formed analytically.
хубав - по-хубав - най-хубав (nice, nicer, the nicest, masculine)
Adverbs in Bulgarian are often formed from adjectives, by adding the ending -o. Another less frequently ending is -e.
бърз - бързо (quick, quickly)
добър - добре (good, well)
There are also adverbs that are not formed from adjectives, like вън (outside), днес (today), etc.
Bulgarian adverbs are pretty flexible when it comes to sentence structure, they can be placed almost anywhere in the sentence.
In the Bulgarian language, there are personal (аз, ти), possessive (мой, твой), interrogative (кой, кого), demonstrative (този, онзи), reflexive (себе си, се), summative (всеки), negative (никой, ничий), indefinite (някой, нечий) and relative (който, чийто) pronouns.
Bulgarian pronouns vary in gender, number, definiteness, and case. They, more than any other part of speech, have preserved the proto-Slavic case system.
Three cases are exhibited by some groups of pronouns – nominative, accusative and dative.
Bulgarian verbs are the most complicated part of Bulgarian grammar. They are inflected for person, number and sometimes gender. They also have lexical aspect (perfective and imperfective), voice, nine tenses, five moods and six non-finite verbal forms. Bulgarian verbs are divided into three conjugations.
Bulgarian verbs express lexical aspect: perfective verbs signify the completion of the action of the verb and form past perfective forms; imperfective ones are neutral with regard to it and form past imperfective forms.
Perfective verbs can usually be formed from imperfective ones by suffixation or prefixation, but the resultant verb often deviates in meaning from the original.
In Bulgarian, there is also grammatical aspect. Three grammatical aspects are distinguishable: neutral, perfect and pluperfect.
There are three grammatically distinctive positions in time – present, past, and future – which combine with aspect and mood to produce a number of formations.
In the indicative mood, there are three simple tenses:
In the indicative there are also the following compound tenses:
There is only one simple tense in the imperative mood, the present. There are compound imperative forms for all persons and numbers in the present compound imperative, the present perfect compound imperative, and the rarely used present pluperfect compound imperative.
The conditional mood consists of five compound tenses, most of which are not grammatically distinguishable.
The subjunctive mood is rarely documented as a separate verb form in Bulgarian, but nevertheless, it is used regularly. The most common form, often mistaken for the present tense, is the present subjunctive.
The inferential mood has five pure tenses. Two of them are simple – past aorist inferential and past imperfect inferential – and are formed by the past participles of perfective and imperfective verbs, respectively. There are also three compound tenses – past future inferential, past future perfect inferential and past perfect inferential.
Some common Bulgarian prepositions are: до, в, около, и, без, между, за, по, вместо, срещу, от, заради, въпреки, през.
This is a very brief overview of Bulgarian grammar. To truly master it, you will need to study each of the parts of speech in much more detail. However, this overview will hopefully give you a general idea of the Bulgarian grammatical system and of the main points you should consider when learning.