Adjectives agree in everything
Russian adjectives must match their noun in gender, number, and case. The good news: there are only three main patterns, and once you spot them you'll predict most forms.
The dictionary form: masculine nominative
Russian dictionaries list the masculine nominative singular: новый (new), большой (big), хороший (good). The ending tells you which pattern the adjective follows.
Pattern 1 — hard stem (-ый / -ая / -ое / -ые)
Most adjectives. Take новый (new): - Masculine: новый стол - Feminine: новая книга - Neuter: новое окно - Plural: новые столы / книги / окна
Pattern 2 — soft stem (-ий / -яя / -ее / -ие)
Adjectives ending in -ний. Take синий (blue): - синий, синяя, синее, синие. The stem ends in a soft consonant, so the endings 'soften' too.
Pattern 3 — stressed -ой ending (большой)
Adjectives where the masculine ending is stressed: -ой instead of -ый. The other forms are normal: - большой, большая, большое, большие. Only the masculine differs from Pattern 1.
Case agreement
When the noun changes case, the adjective changes too: У меня новая книга (nom) → Я читаю новую книгу (acc) → У меня нет новой книги (gen). The full case table is a separate memorization, but the rule is simple: adjective follows its noun.
