The parts of speech in Bulgarian are divided in 10 different types, which are categorized in two broad classes: mutable and immutable. The difference is that mutable parts of speech vary grammatically, whereas the immutable ones do not change, regardless of their use. The five classes of mutables are: nouns, adjectives', numerals, pronouns and verbs. Syntactically, the first four of these form the group of the noun or the nominal group. The immutables are: adverbs, prepositions, conjunctions, particles and interjections. Verbs and adverbs form the group of the verb or the verbal group.
Nouns and adjectives have the categories grammatical gender, number, case (only vocative) and definiteness in Bulgarian. Adjectives and adjectival pronouns agree with nouns in number and gender. Pronouns have gender, number and retain (as in nearly all Indo-European languages) a more significant part of the case system.
There are three grammatical genders in Bulgarian: masculine, feminine and neuter. The gender of the noun can largely be determined according to its ending. The vast majority of Bulgarian nouns ending in a consonant ("zero ending") are masculine (for example, град "city", син "son", мъж "man"). Feminine nouns include almost all nouns that have the endings –а/–я (жена "woman", дъщеря "daughter", улица "street"), a large group of nouns with zero ending expressing quality, degree or an abstraction, including all nouns ending on –ост/–ест (мъдрост "wisdom", низост "vileness", прелест "loveliness", болест "sickness", любов "love"), and another, much smaller group of irregular nouns with zero ending which define tangible objects or concepts (кръв "blood", кост "bone", вечер "evening"). Nouns ending in –е, –о are almost exclusively neuter (дете “child”, езеро "lake"). The same regards a limited number of loan words ending in –и, –у, and –ю (цунами "tsunami", табу "taboo", меню "menu"). The plural forms of the nouns do not express their gender clearly, although the ending –и is more likely to be used with a masculine or feminine noun (факти "facts", болести "sicknesses"), while one in –а/–я belongs more often to a neuter noun (езера "lakes"). Also, plural ending –ове occurs only in masculine nouns. The Bulgarain language has many different ways of expressing the plurality of a noun. For example the word клон (branch) has two ways to be plural. The first one is клони, where it defines many branches of a tree or a bush. But it may take -ове and may become клонове, where the word means many branches of a bank, or a factory or in its industry meaning. There are many irregular formations of plurals. Besides it is an exception according to its grammar gender, the word чичо (uncle), which is masculine, generates its plural form irregularly - it becomes чичовци, not чичи or чичове.
Two numbers are distinguished in Bulgarian — singular and plural. A variety of plural suffixes is used, and the choice between them is partly determined by their ending in singular, partly influenced by gender and partly impredictible due to the commonness of exceptions, irregular declension and alternative plural forms. Words ending in –а/–я (which are usually feminine) generally have the plural ending –и, upon dropping of the singular ending. Of nouns ending in a consonant, the feminine ones also use –и, whereas the masculine ones usually have –и for polysyllables and –ове for monosyllables (however, exceptions are especially common in this group). Nouns ending in –о/–е (most of which are neuter) use the suffixes –а, –я (both of which require the dropping of the singular endings) and –та.
With cardinal numbers and related words such as няколко ("several"), masculine nouns use a separate count form in –а/–я, which stems from the proto-Slavonic dual: двама/трима ученици (two/three students) versus тези ученици (these students); cf. feminine две/три/тези жени (two/three/these women) and neuter две/три/тези деца (two/three/these children). However, a recently developed language norm requires that count forms should only be used with masculine nouns that do not denote persons. Thus, двама/трима ученици is perceived as more correct than двама/трима ученика, while the distinction is retained in cases such as два/три молива (two/three pencils) versus тези моливи (these pencils).
The complex proto-Slavonic case system is almost completely dissolved in modern Bulgarian and has been replaced by prepositional and other syntactic constructions. Cases are well preserved only in the personal pronouns (as they are in most or all Indo-European languages), with nominative, accusative, dative and vocative forms. Vestiges are present in the masculine personal interrogative pronoun кой ("who") and in a number of phraseological units and sayings. Vocative forms are still in use for masculine (with the endings -e, -o and -ю) and feminine nouns (-[ь/й]o and -e) in the singular, although there is a tendency to avoid them in many personal names, as the use of feminine name forms in -[ь/й]o and of the potential vocative forms of foreign names has come to be considered rude or rustic. The vocative case is used usually for men, not for women, because it may offend the lady. It is not known in many languages. It's usually used in spoken language and in literary works, associated with past times in the Bulgarian history and customs. "Иване" means "Hey, Ivan", and defines to whom the speaker is talking exactly! The form "Марийо" is "Hey, Maria" is not usually used.
In modern Bulgarian, definiteness is expressed by a definite article which is postfixed to the noun, much like in the Scandinavian languages or Romanian (indefinite: човек, "man"; definite: човекът, "the man") or to the first nominal constituent of definite noun phrases (indefinite: добър човек, "a good man"; definite: добрият човек, "the good man"). There are four singular definite articles. Again, the choice between them is largely determined by the noun's ending in the singular. Nouns that end in a consonant and are masculine use –ът/–ят, when they are grammatical subjects, and –а/–я, when they are grammatical objects. Nouns that end in a consonant and are feminine, as well as nouns that end in –а/–я (most of which are feminine, too) use –та. Nouns that end in –е/–о use –то.
The plural definite article is –те for all nouns except for those, whose plural form ends in –а/–я; these get –тa instead. When postfixed to adjectives the definite articles are –ят/–я for masculine gender, –та for feminine gender, –то for neuter gender, and –те for plural.
Both groups agree in gender and number with the noun they are appended to. They may also take up the definite article as explained above.
Pronouns may vary in gender, number, definiteness and are the only parts of speech that have retained case inflexions. Three cases are exhibited by some groups of pronouns, nominative, accusative and dative, although dative is often substituted by accusative constructions. The distinguishable types of pronouns include the following: personal, relative, reflexive, interrogative, negative, indefinitive, summative and possessive.
Finite verbal forms are simple or compound and agree with subjects in person (first, second and third) and number (singular, plural) in Bulgarian. In addition to that, past compound forms using participles vary in gender (masculine, feminine, neuter) and voice (active and passive) as well as aspect (perfective/aorist and imperfective).
Bulgarian verbs express lexical aspect: perfective verbs signify the completion of the action of the verb and form past aorist tenses; imperfective ones are neutral with regard to it and form past imperfect tenses. Most Bulgarian verbs can be grouped in perfective-imperfective pairs (imperfective<>perfective: идвам<>дойда "come", пристигам<>пристигна “arrive”). Perfective verbs can be usually formed from imperfective ones by suffixation or prefixation, but the resultant verb often deviates in meaning from the original. In the pair examples above, aspect is stem-specific and therefore there is no difference in meaning.
In Bulgarian, there is also grammatical aspect. Three grammatical aspects are distinguishable: neutral, perfect and pluperfect. The neutral aspect comprises the three simple tenses and the future tense. The pluperfect aspect is manifest in tenses that use double or triple auxiliary "be" participles like the past pluperfect subjunctive. Perfect tenses use a single auxiliary "be".
In addition to the four moods (наклонения) shared by most other European languages - indicative (изявително), imperative (повелително), subjunctive (подчинително) and conditional (условно) - in Bulgarian there is one more to describe past unwitnessed events - the renarrative (преизказно) mood.
There are three grammatically distinctive positions in time — present, past and future — which combine with aspect and mood to produce a number of formations. Normally, in grammar books these formations are viewed as separate tenses — i. e. "past imperfect tense" would mean that the verb is in past tense, in the imperfective aspect, and in the indicative mood (since no other mood is shown). There are more than 30 different tenses across Bulgarian's two aspects and five moods.
In the indicative mood, there are three simple tenses:
* Present tense is a temporally unmarked simple form made up of the verbal stem of and a complex suffix composed of the vowel /e/, /i/ or /a/ and the person/number ending (пристигам "I arrive/I am arriving"); only imperfective verbs can stand in the present indicative tense independently;
* Past imperfect tense is a simple verb form used to express an action which is contemporaneous or subordinate to other past actions; it is made up of an imperfective or a perfective verbal stem and the person/number ending (пристигаx, пристигнеx "I was arriving");
* Past aorist tense is a simple form used to express a temporarily independent, specific past action; it is made up of a perfective or an imperfective verbal stem and the person/number ending (пристигнах "I arrived", четох "I read");
In the indicative there are also the following compound tenses:
* future tense is a compound form made of the particle ще and present tense (ще уча "I will study"); negation is expressed by the construction няма да and present tense (няма да уча or the old-fashined form "не ще да уча" - "I will not study");
* Past future tense is a compound form used to express an action which was to be completed in the past but was future as regards another past action; it is made up of the past imperfect tense of the verb ща "will, want", the particle да "to" and the present tense of the verb (щях да уча "I was going to study");
* Present perfect tense is a compound form used to express an action which was completed in the past but is relevant for or related to the present; it is made up of the present tense of the verb съм "be" and the past participle (съм учил "I have studied");
* Past perfect tense is a compound form used to express an action which was completed in the past and is relative to another past action; it is made up of the past tense of the verb съм "be" and the past participle (бях учил "I had studied");
* Future perfect tense is a compound form used to express an action which is to take place in the future before another future action; it is made up of the future tense of the verb съм "be" and the past participle (ще съм учил "I will have studied");
* Past future perfect tense is a compound form used to express a past action which is future with respect to a past action which itself is prior to another past action; it is made up of the past imperfect of ща "will, want", the particle да "to", the present tense of the verb съм "be" and the past participle of the verb (щях да съм учил "I would have studied").
The four perfect tenses above can all vary in aspect depending on the aspect of the main-verb participle; they are in fact pairs of imperfective and perfective tenses. Verbs in tenses using past participles also vary in voice and gender.
There is only one simple tense in the imperative mood - the present - and there are simple forms only for the second person using the suffixes -и/-й for singular and -ете/-йте for plural; e.g., уча "to study": учи, sg., учете, pl.; играя "to play": играй, играйте. There are compound imperative forms for all persons and numbers in the present compound imperative (да играе) and the present perfect compound imperative (да е играл).
The conditional mood consists of five compound tenses, most of which are not grammatically distinguishable. The present, future and past conditional use a special past form of the stem би- ("be") and the past participle (бих учил, "I would study"). The past future conditional and the past future perfect conditional coincide in form with the respective indicative tenses.
The subjunctive mood is rarely documented as a separate verb form in Bulgarian, (being, morphologically, a sub-instance of the quasi-infinitive construction with the particle да "to" and a normal finite verb form), but nevertheless it is used regularly. The most common form, often mistaken for the present tense, is the present subjunctive ((пo-добре) да отидa "I had better go"). The difference between the present indicative and the present subjunctive tense is that the subjunctive can be formed by both perfective and imperfective verbs. It has completely replaced the infinitive and the supine from complex expressions (see below). It is also employed to express opinion about possible future events. The past perfect subjunctive ((пo-добре) да бях отишъл, "I had better gone") refers to possible events in the past, which did not take place, and the present pluperfect subjunctive (да съм бил отишъл), which may be used about both past and future events arousing feelings of incontinence, suspicion, etc. and is impossible to translate in English. This last variety of the subjunctive in Bulgarian is sometimes also called the dubitative mood.
The renarrative mood has five tenses. Two of them are simple - past aorist renarrative and past imperfect renarrative - and are formed by the past participles' of perfective and imperfective verbs, respectively. There are also three compound tenses - past future renarrative, past future perfect renarrative and past perfect renarrative. All these tenses' forms are gender-specific in the singular and exist only in the third person. The existence of renarrative forms has been attributed to Turkish influences by most Bulgarian linguists. Morphologically, they are related to the perfect tenses.
The proto-Slavonic infinitive and supine have been replaced by phrases with да ("to") and present subjunctive tense (искам да уча, "I want to study").
Bulgarian has the following participles:
* Present active participle (сегашно деятелно причастие) is formed from imperfective stems with the addition of the suffixes –ащ/–ещ/–ящ (укриващ, "concealing") and is used only attributively;
* Present passive participle (сегашно страдателно причастие) is formed by the addition of the suffix -н to imperfective stems (укриван, "(being) concealed");
* Past active aorist participle (минало свършено деятелно причастие) is formed by the addition of the suffix –л– to perfective stems (укрил, "concealed");
* Past active imperfect participle (минало несвършено деятелно причастие) is formed by the addition of the suffixes –ел/–ал/–ял to imperfective stems (укривал, "(been) concealing"); it is used only in renarrative (renarrated) mood and is a Bulgarian innovation;
* Past passive participle' (минало страдателно причастие) is formed from aorist stems with the addition of the suffixes –(е)н–/–т– (укрит, "(been) concealed"); it is used predicatively and attributively;
* Adverbial participle (деепричастие) is formed from imperfective present stems with the suffix –(е)йки (укривайки, "while concealing"), relates an action contemporaneous with and subordinate to the main verb and is originally a Western Bulgarian form.
The participles are inflected by gender, number, and definiteness, and are coordinated with the subject when forming compound tenses (see tenses above). When used in attributive role the inflection attributes are coordinated with the noun that is being attributed.
The most productive way to form adverbs is to derive them from the neuter singular form of the corresponding adjective (бързо (fast), силно (hard), странно (strange)), although adjectives ending in -ки use the masculine singular form, also in -ки, instead: юнашки (heroically), мъжки (bravely, like a man), майсторски (skilfully). The same pattern is used to form adverbs from the (adjective-like) ordinal numerals, e.g. първо (firstly), второ (secondly), трето (thirdly), and in some cases from (adjective-like) cardinal numerals, e.g. двойно (twice as/double), тройно (three times as), петорно (five times as).
The remaining adverbs are formed in ways that are no longer productive in the language. A small number are original (not derived from other words), for example: тук (here), там (there), вътре (inside), вън (outside), много (very/much) etc. The rest are mostly fossilized declined forms, such as:
* archaic unchangeable locative forms of some adjectives, e.g. добре (well), зле (badly), твърде (too, rather), and nouns горе (up), утре (tomorrow), лете (in the summer);
* archaic unchangeable instrumental forms of some adjectives, e.g. тихом (quietly), скришом (furtively), слепешком (blindly), and nouns, e.g. денем (during the day), нощем (during the night), редом (one next to the other), духом (spiritually), цифром (in figures), словом (with words). The same pattern has been used with verbs: тичешком (while running), лежешком (while lying), стоешком (while standing).
* archaic unchangeable accusative forms of some nouns: днес (today), сутрин (in the morning), зимъс (in winter);
* archaic unchangeable genitive forms of some nouns: довечера (tonight), снощи (last night), вчера (yesterday);
* homonymous and etymologically identical to the feminine singular form of the corresponding adjective used with the definite article: здравата (hard), слепешката (gropingly); the same pattern has been applied to some verbs, e.g. тичешката (while running), лежешката (while lying), стоешката (while standing).
* derived from cardinal numerals by means of a non-productive suffix: веднъж (once), дваж (twice), триж (thrice);