How to Form Irregular French Adjectives

Some French adjectives have irregular feminine singular endings. To form the feminine singular form, some masculine singular adjectives require a little more than just adding -e. Here, the irregular feminine adjectives are in nine categories based on verb ending so they’re easier for you to spot.

• Ending in vowel + consonant: For adjectives that end in a vowel + consonant, you form the FS adjective by doubling that consonant before adding the -e of the feminine singular. Some examples include ancien (old/former) to ancienne, exceptionnel (exceptional) to exceptionnelle, and net (clear) to nette.

  This rule has exceptions, and not all adjectives ending in vowel + consonant double that consonant before the -e of the feminine. Here are a few examples: féminin (feminine) to feminine, fin (fine) to fine, normal (normal) to normale, brun (dark-haired) to brune, and gris (gray) to grise.

• Ending in -eur or -eux: For adjectives that end in -eur or -eux, replace the masculine singular ending with -euse to form the feminine singular. Some examples include fumeur (smoking) to fumeuse and luxueux (luxurious) to luxueuse.

  This rule also has exceptions, and not all adjectives in -eur turn to -euse in the feminine. For some, just add -e to the masculine -eur form: inférieur (inferior) becomes inférieure, supérieur (superior) becomes supérieure, intérieur (interior) becomes intérieure, and meilleur (better) changes to meilleure.

• Ending in -teur: For adjectives that end in -teur, replace -teur with -trice to form the feminine singular, like protecteur (protective) to protectrice, conservateur (conservative) to conservatrice, and indicateur (indicative) to indicatrice.

• Ending in -er: For adjectives that end in -er, replace -er with -ère to form the feminine singular, like dernier (last) to dernière, premier (first) to première, and cher (expensive) to chère.

• Ending in -et: For adjectives that end in -et, replace -et with -ète to form the feminine singular, like discret/discrète (discreet), complet/complète (complete), and secret/secrète (secret).

• Ending in -f: For adjectives that end in -f, replace -f with -ve to form the feminine singular, like neuf to neuve (new), naïf to naïve (naive), négatif to négative (negative), and sportif to sportive (athletic).

• Ending in -on or -ien: For adjectives that end in -on or -ien, double the -n before adding the -e to form the feminine singular, like mignon to mignonne (cute).

  Many adjectives of nationality and regionality are in this category, like canadien/canadienne (Canadian), parisien/parisienne (Parisian), and italien/italienne (Italian). However, adjectives of nationality that end in -ain, like américain/américaine (American), mexicain/mexicaine (Mexican), and marocain/marocaine (Moroccan) don’t double the -n. (Note that English capitalizes adjectives refering to nationalities and religions, but French doesn’t.)

• Some adjectives have a completely irregular form that doesn’t follow any pattern.