beau before a masculine singular noun beginning with a consonant
bel before a masculine singular noun beginning with a vowel or ‘h’ mute
beaux before masculine plural nouns
belle before a feminine singular noun
belles before feminine plural nouns
Un beau chapeau
Un bel enfant
Une belle robe
nouveau (new) before a masculine singular noun beginning with a consonant
nouvel before a masculine singular noun beginning with a vowel or ‘h’ mute
nouveaux before masculine plural nouns
nouvelle before a feminine singular noun
nouvelles before feminine plural nouns
Un nouveau chapeau
Un nouvel habit
Une nouvelle robe
Vieux before a masculine singular noun beginning with a consonant
vieil before a masculine singular noun beginning with a vowel or ‘h’ mute
vieux before masculine plural nouns
vieille before a feminine singular noun
vieilles before feminine plural nouns