Conventionally, Russian nouns have six cases: nominative case, genitive case, dative case, accusative case, instrumental case, and prepositional case. However, some nouns retain vestiges of Old Russian vocative case, and some have acquired a partitive-genitive case separate from the genitive and/or a locative case separate from the prepositional.

The nominative case is the subject case, and this is considered the basic form of a word:

The genitive case is similar to the English possessive case, and it often corresponds to English of or the possessive ending ’s:

The dative case is similar to the English indirect object, and it often corresponds to the words to or towards:

The accusative case is like the English direct object, although in some cases describes motion:

The instrumental case indicates the agent or the instrument of an action, and it often corresponds to English with or by:

The prepositional case always takes a preposition, and it often indicates location:

The partitive-genitive case, when different from the genitive, means part of something, some of something:

The locative case, when it differs from the prepositional case, indicates location:

The vocative case survives in only a few words of a religious nature, and this case marks the person being addressed. In some old writing and in some poetry, this is sometimes indicated with the word "O" or "Oh" in English:

In addition, there is a new colloquial vocative case used with some names or family members ending in -а or -я, a so-called "new vocative". It's formed by dropping the final -а or -я, -я is changed to -ь, for example:

This is not considered very standard. These forms are normally not included in dictionaries and formally the nominative case is used for this purpose.

Russian nouns are frequently irregular in declension, and specific declensions may be found in most articles. Listed here are what we consider to be standard regular declensions:

Nouns that end in a hard consonant or the vowels -а or -о are hard and follow these hard patterns:

1. Hard feminine case endings:

• Examples:

  газе́та (gazéta)

  рабо́та (rabóta)

  сестра́ (sestrá)

N.B.—Nouns that end (after dropping the final vowel in the case of feminines or neuters) in the consonants -г, -к, -х, -ж, -ч, -ш, or -щ are also hard, but they take soft -и instead of -ы in the applicable cases:

2. Hard feminine case endings with -и:

• Examples:

  кни́га (kníga)

  копе́йка (kopéjka)

Feminine nouns in -я follow these soft patterns:

3. Soft feminine case endings:

• Examples:

  исто́рия (istórija)

  неде́ля (nedélja)

  ня́ня (njánja)

1. Hard masculine case endings:

• Examples:

  вид (vid)

  журна́л (žurnál)

  оте́ц (otéc)

  стол (stol)

2. Hard neuter case endings:

• Examples:

  блю́до (bljúdo)

  жили́ще (žilíšče)

  окно́ (oknó)

  письмо́ (pisʹmó)

  учи́лище (učílišče)

N.B.—Nouns that end (after dropping the final vowel in the case of feminines or neuters) in the consonants -г, -к, -х, -ж, -ч, -ш, or -щ are also hard, but they take soft -и instead of -ы in the applicable cases:

3. Hard masculine case endings with -и:

• Examples:

  бог (box) (irregular pronunciation in the nominative singular)

  каранда́ш (karandáš)

  нож (nož)

  това́рищ (továrišč)

  уро́к (urók)

Masculine nouns that end in -й or -ь, neuter nouns in -е follow these soft patterns.

4. Soft masculine case endings:

• Examples:

  апре́ль (aprélʹ)

  геро́й (gerój)

  день (denʹ)

  слова́рь (slovárʹ)

  слу́чай (slúčaj)

  учи́тель (učítelʹ)

  чай (čaj)

5. Soft neuter case endings:

• Examples:

  мо́ре (móre)

  по́ле (póle)

  уче́ние (učénije)

Feminine nouns in -ь belong to the third declension:

• Examples:

  дверь (dverʹ)

  ло́шадь (lóšadʹ)

The following codes are used in declension tables, in the following order:

1. animacy: anim = animate, inan = inanimate, bian = bianimate (can be both animate and inanimate)

   • this affects the accusative plural and masculine accusative singular, which are the same as the nominative in inanimates and the genitive in animates

2. number restriction: pl-only = plural only (plurale tantum), sg-only = singular only (singulare tantum)
3. typical gender: masc-type = typically masculine, fem-type = typically feminine, neut-type = typically neuter

   • this refers to the form of the noun, not the actual gender, which in some cases is different

4. stem class or declension:
   1. stem values: hard-stem = ends in a paired hard consonant, soft-stem = ends in a paired soft consonant, velar-stem = ends in к/г/х, sibilant-stem = ends in ш/щ/ч/ж, ц-stem = ends in ц, vowel-stem = ends in a vowel other than и or ends in a palatal (й or ь + vowel), i-stem = ends in и

      • this affects the form that various endings take

   2. other values: 3rd-decl = 3rd-declension noun (feminine in -ь or neuter in -мя), invar = invariable, short poss = short possessive adjectival, mixed poss = mixed possessive adjectival, proper poss = proper-noun possessive adjectival

      • all the adjectival variants here have short (noun-like) endings in some of their cases, and the stem generally ends in -ов/ев/ёв or -ин

5. accent specifies the stress pattern: a, b, b', c, d, d', e, f, f', f''

   • see Appendix: Russian stress patterns
   • more than one is possible

6. adj = adjectival (has the endings of an adjective rather than a typical noun)
7. reduc = reducible, [reduc] = optionally reducible

   • this means that an extra vowel appears before the final stem consonant in the nominative singular and/or genitive plural (specifically, in all endings lacking a vowel)

8. irreg = irregular

   • most commonly, this refers to an unexpected nominative plural or genitive plural ending, or a special plural stem

• Wiktionary:Russian templates
• Appendix:Russian stress patterns
• Russian declension on Wikipedia.Wikipedia