Adjective agreement
Summary
French adjectives change form to agree in gender and number with the noun they describe, usually adding -e for the feminine and -s for the plural.
Explanation
A French adjective agrees with its noun in both gender and number. The basic pattern adds -e for the feminine and -s for the plural, giving up to four written forms: un petit chat, une petite chatte, des petits chats, des petites chattes. The plural -s and the feminine -e are often heard only in the feminine, where the added -e makes a previously silent consonant sound (petit /pəti/ vs petite /pətit/).
Two forms are already 'full' and barely change. An adjective ending in -e in the masculine (rouge, jeune, facile) is identical in the feminine: un mur rouge, une porte rouge. An adjective ending in -s or -x in the masculine singular adds nothing in the masculine plural: un cas précis → des cas précis, un homme heureux → des hommes heureux.
Many adjectives have irregular feminines that you must learn as patterns: -eux → -euse (heureux → heureuse), -f → -ve (neuf → neuve, sportif → sportive), -er → -ère (cher → chère, premier → première), and several with a doubled consonant (bon → bonne, gros → grosse). A few are wholly irregular (beau → belle, vieux → vieille, blanc → blanche), and colours derived from nouns are invariable (des chaussures marron, des yeux orange).
The main pitfall for English speakers is forgetting agreement altogether, since English adjectives never change: une voiture vert is wrong for une voiture verte. A second pitfall is mixed-gender groups — when an adjective qualifies several nouns of different genders, it goes to the masculine plural (Paul et Marie sont contents). Rule of thumb: identify the noun's gender and number first, then choose the matching adjective form, and check whether the feminine is regular (-e) or one of the irregular families.
Examples
un petit chat, une petite chatte — a small (male) cat, a small (female) cat (Feminine adds -e.)
des voitures vertes — green cars (Feminine plural: -e + -s.)
un mur rouge, une porte rouge — a red wall, a red door (Adjective in -e: no change in the feminine.)
une femme heureuse — a happy woman (Irregular feminine: -eux becomes -euse.)
Paul et Marie sont contents. — Paul and Marie are happy. (Mixed-gender group takes the masculine plural.)
Common mistakes
une voiture vert
une voiture verte
English adjectives never change, so learners leave the French adjective in its bare masculine form. But a French adjective must agree with its noun: with the feminine noun voiture, vert takes an -e and becomes « une voiture verte ». Add -e for the feminine and -s for the plural (« des voitures vertes »). The habit to build is to check the noun's gender and number every time, not just translate the adjective.
Prerequisites
Related rules
adjectivesagreementgender