Accusative direct object

The Accusative case (винительный падеж) is primarily used for the direct object of transitive verbs. It answers the questions Кого? (Whom? - from кто) and Что? (What? - from что). A direct object in Russian is used without a preposition, though the Accusative case itself is frequently used with prepositions for other functions (like direction).

The endings depend on the noun's gender and animacy:

• Feminine and masculine nouns ending in -а/-я: This includes feminine nouns and masculine nouns like 'папа' or 'дядя'. The ending -а changes to -у, and -я changes to -ю.
• Masculine Singular: If it is a thing (inanimate), it stays the same as the Nominative. If it is a person or animal (animate), it takes the Genitive ending (adding -а to consonants, or replacing -й/-ь with -я; note that some nouns drop a vowel before adding the ending, like отец → отца).
• Neuter Singular: Always stays the same as the Nominative.
• Feminine nouns ending in a soft sign (-ь): Do not change in the singular.
• Plural: For all genders, inanimate plurals look like the Nominative; animate plurals look like the Genitive Plural. Note that while this animacy rule applies to all plural nouns, the specific Genitive Plural endings still depend on the noun's gender and declension class.

Adjectives: Adjectives must match the noun. Feminine adjectives change to -ую/-юю (and those ending in -ья change to -ью, like третья → третью). Masculine animate adjectives take -ого/-его (use -его after soft consonants and after sibilants like ж, ш, ч, щ, ц when unstressed, e.g., хорошего), while inanimate ones stay like the Nominative (-ый / -ий / -ой). Neuter adjectives stay the same as the Nominative (-ое/-ее). In the plural, gender distinctions disappear: animate plural adjectives of all genders take -ых/-их, while inanimate plural adjectives stay like the Nominative (-ые/-ие). Remember the 7-letter spelling rule: after г, к, х, ж, ч, ш, щ, always use -ие/-их instead of -ые/-ых. Note that adjectives modifying masculine nouns ending in -а/-я (like папа) take masculine animate endings (e.g., Я вижу моего старого дедушку).

Possessive and Demonstrative Pronouns: Words like мой, твой, наш, ваш (my, your, our, your) and этот, тот (this, that) must also match the noun's case and animacy, declining similarly to adjectives.

Personal Pronouns: Pronouns also change to show the direct object: я → меня, ты → тебя, он → его, она → её, оно → его, мы → нас, вы → вас, они → их, and the reflexive pronoun себя (oneself) takes the form себя. Note that third-person pronouns (его, её, их) never take the added 'н-' prefix (него, неё, них) when used as direct objects, because direct objects do not use prepositions.

Note: Grammatical animacy doesn't always match biology. For example, words like кукла (doll), робот (robot), and мертвец (dead body) are treated as animate (Accusative = Genitive), while words like труп (corpse), народ (people/nation), and толпа (crowd) are treated as inanimate (Accusative = Nominative). Also, direct objects can sometimes take the Genitive case instead of Accusative when the verb is negated (e.g., Я не вижу книги) or when referring to 'some' of an uncountable mass (e.g., Я выпил воды).