Noun Irregularities

1. The Genitive II. There is a small group of nouns, mostly referring to food, which use the suffix -y for the Genitive Singular. Not all nouns referring to food take this Genitive II ending, so you will have to memorize those that do.

2. The Prepositional II. The second Prepositional case is marked by an (always) accented ending -y. However, this ending is not used with all the prepositions requiring the Prepositional case but only with the prepositions на and в. It is not used with the preposition o or any other preposition governing the Prepositional case. So one would say я видел его в саду 'I saw him in the garden' but мы говорили о саде 'we talked about the garden'.

3. Masculine Plurals on -a. The ending -a was originally a Dual Number ending, marking two objects when all Russian nouns had Singular, Dual, and Plural forms. For that reason, almost all masculine nouns which come in pairs (eyes, horns, banks of rivers) use this ending. Now, however, it is not only a wide-spread Nominative Plural ending, it is often attached to new words entering the language, so it is productive. Here are a few common nouns that it is used with.

4. Masculine Nouns with Plurals in -ья. Nouns which take -ья as an ending are, fortuntely, few in number. Remember, however, that if a noun takes this ending in the Nominative Plural and the ending is accented, the Genitive Plural will be -ей (remove the soft sign); if the ending is not accented, the Genitive Plural ending will be -ьев.

5. Masculine Nouns with the Singular Suffix -ин. There is also a subregular set of nouns with a singular suffix that disappears in the plural. Moreover, the Nominative Plural ending for these nouns is -e and the Genitive Plural ending is zero, i. e. no ending at all.

Otherwise, these nouns decline normally in the singular and plural.

Notice the following. In the masculine, all the endings are noun endings except in the Instrumental. In the Feminine, all the endings are adjectival except for the Nominative and Accusative. In the Plural, all endings are adjectival except the Nominative.