1. Nominative Plural of Nouns
Это лампа. Это лампы.

Nominative singular is the main form of nouns and adjectives (nouns and adjectives given in dictionaries are in the nominative singular). You have seen the nominative singular of nouns in sentences like: Это лампа. - This is a lamp; Это учебник. - This is a textbook.
From this lesson you will learn how to say: These are lamps; These are textbooks, i.e. how to make nouns plural. Remember the rules below.
To form the nominative plural of most masculine and feminine nouns replace the nominative singular ending by -ы for hard stems and -и for soft stems.

• Hard stem
• Singular -> Plural
• Soft stem
• Singular -> Plural
• Masculine
• журнал - журналы
• музей - музеи
• magazine(-s), museum(-s)
• словарь - словари
• dictionary(-ies)
• Feminine
• лампа - лампы
• песня - песни
• lamp(-s), song(s)
• дверь - двери
• door(-s)
• Plural ending -ы -и

To form the nominative plural of neuter nouns replace the nominative singular ending by -а for hard stems and -я for soft stems:

• Hard stem
• Singular -> Plural
• Soft stem
• Singular -> Plural
• Neuter
• письмо - письма
• ружьё - ружья
• letter(-s), gun(-s)
• платье - платья
• dress(-es)
• Plural ending -а -я

Notes
Hard stem masculine nouns have zero ending (no ending), so we simply add -ы to form the plural (in other words, we replace zero by -ы): журналØ -> журналы.
A soft stem is a stem that ends in a soft consonant. The letter ь and the vowel letters я, е, ё, ю, и indicate that the preceding consonant is soft. If there is no one of these six letters at the end of the stem, we assume that the stem is hard.
When forming the nominative plural of nouns never break the 7-letter spelling rule: after г, к, х, ж, ш, щ, ч write -и , not -ы (no matter if the stem is hard or soft): книга - книги (books), учебник - учебники (textbooks), стих - стихи (poems), нож - ножи (knives), карандаш - карандаши (pencils), etc.

Some Russian nouns shift their accent (stress) in the plural. Such words are marked in the dictionaries. Click the following words to listen, pay attention to the stress shift in the plural:

• карандаш - карандаши
• pencil(s)
• словарь - словари
• dictionarie(s)
• письмо - письма
• letter(s)
• ружьё - ружья
• gun(s)
• окно - окна
• window(s)

Masculine nouns with stems that end in -ок or -ец lose the vowels о, е whenever an ending is added. Compare the singular and plural forms of nouns напиток (a drink), подарок (a gift), огурец (a cucumber), канадец, (Canadian).

• напиток - напитки
• drink(s)
• подарок - подарки
• gift(s)
• огурец - огурцы
• cucumber(s)
• канадец - канадцы
• canadian(s)

For some nouns denoting profession or occupation plurals are formed from both masculine and feminine forms. Study the usage of the plurals студенты and студентки:
Том студент и Иван студент. Инна студентка и Анна студентка.

Том и Иван студенты
(A group of male students)
Инна и Анна студентки .
(A group of female students)
Том, Иван, Инна и Анна студенты.
(A group of male and female students)

Русский язык для иностранцев в Алматы

Источник: russianforeveryone.com