Most French adjectives are regular, but there are a number of irregular adjectives, based on the final letter(s) of the masculine singular adjective.
Adjectives that end in a vowel plus L or N usually become feminine by doubling the consonant before adding E.
Ending: el > elle Adjective: personnel (personal)
Masculine singular personnel
Feminine singular personnelle
Masculine plural personnels
Feminine plural personnelles
Ending: on > onne Adjective: bon (good)
Masculine singular bon
Feminine singular bonne
Masculine plural bons
Feminine plural bonnes
Adjectives that end in er or et need a grave accent:
Ending: er > ère Adjective: cher (expensive)
Masculine singular cher
Feminine singular chère
Masculine plural chers
Feminine plural chères
Ending: et > ète Adjective: complet (full)
Masculine singular complet
Feminine singular complète
Masculine plural complets
Feminine plural complètes
Other final letters lead to very irregular feminine endings:
Ending: c > che Adjective: blanc (white)
Masculine singular blanc
Feminine singular blanche
Masculine plural blancs
Feminine plural blanches
Ending: eur > euse Adjective: flatteur (flattering)
Masculine singular flatteur
Feminine singular flatteuse
Masculine plural flatteurs
Feminine plural flatteuses
Ending: eux > euse Adjective: heureux (happy)
Masculine singular heureux
Feminine singular heureuse
Masculine plural heureux
Feminine plural heureuses
Ending: f > ve Adjective: neuf (new)
Masculine singular neuf
Feminine singular neuve
Masculine plural neufs
Feminine plural neuves
Irregular plurals: The ending al changes to aux in the plural:
Adjective: idéal (ideal)
Masculine singular idéal
Feminine singular idéale
Masculine plural idéaux
Feminine plural idéales
Note: Most of the above rules are the same for making nouns feminine and plural.
Irregular French adjectives
There are several French adjectives which have irregular feminine and plural forms, as well as a special form when they are placed in front of a masculine noun that begins with a vowel or a mute H:
un bel homme - a handsome man
un vieil ami - an old friend
| Singular | Plural | ||||
| Adjective | masc | vowel/H | fem | masc | fem |
| beautiful | beau | bel | belle | beaux | belles |
| new | nouveau | nouvel | nouvelle | nouveaux | nouvelles |
| crazy | fou | fol | folle | fous | folles |
| soft | mou | mol | molle | mous | molles |
| old | vieux | vieil | vieille | vieux | vieilles |
