What is an adjective and its agreement with a noun

Hello, dear student!

Today I would like to write about an adjective (имя прилагательное [imya prilagatel'noe]) in the Russian language.
Russian-speaking people use an adjective to denote an attribute (of a person or an object), but the most important thing you should memorize and always know is that an adjective agrees with a noun in gender, number and case. You might ask: "What does it mean?". Adjectives are actually always used in a sentence with nouns, for example:

Красивое платье (A beautiful dress) = красивое [krasivae] is an adjective + платье [plat'e] is a noun.
The adjective and the noun are pair in this sentence. So before we determine form of an adjective and write correct inflexion, we should look at a noun which is paired up with this adjective – we should determine a number, gender and case. In our example the noun is singular, belongs to neuter gender and is in the nominative case.

Let's inflect some examples for cases to write correct inflexions of adjectives:

1. Именительный падеж [Iminitel'nyj padezh] - Nominative case
Это новАЯ сумка [Ehta novaya sumka] - This is a new bag

We can see that the noun Сумка (bag) belongs to feminine gender, singular and we know, the feminine gender usually has inflexions -А/Я, so we write analogous inflexion in the adjective (q.v. the article about adjectives by the example of colors).

2. Родительный падеж [Raditel'nyj padezh] - Genitive case
У меня нет новОГО карандаша [U menya net novava karandasha] - I don't have a new pencil

We see in this example, the word "карандаш" (pencil) is in the genitive case, so we put the adjective in the same form, and if an adjective is in the genitive case, it acquires the inflexion -ОГО because the word "карандаш" belongs to masculine gender.

3. Дательный падеж [Datel'nyj padezh] - Dative case

Я подошел к красивОМУ дереву [Ya padashol k krasivamu derevu] - I came to the beautiful tree.

The adjective will end with the inflexion -ОМУ in the dative case because the noun "дерево" (tree) belongs to neuter gender.

Thus, we can draw up a table (in the Nominative case) which will reflect important inflexion changes of adjectives for genders:

Мужской род (Male)	Женский род (Female)	Средний род (Neuter)	Множественное число (Plural form)
Какой? [Kakoj?]	Какая [Kakaya?]	Какое [Kakoe?]	Какие [Kakie?]
НовЫЙ	НовАЯ	НовОЕ	НовЫЕ
СтарЫЙ	СтарАЯ	СтарОЕ	СтарЫЕ
ХорошИЙ	ХорошАЯ	ХорошЕЕ	ХорошИЕ

Sometimes you may meet the inflexion -ОЙ in the column with masculine gender, e.g.
ПлохОЙ [Plakhoj] – Bad