French Adjectives Ending in -l

French adjectives ending in -l vary in how they form the feminine. Most simply add -e: fatal → fatale. However, all -el adjectives double the -l (actuel → actuelle), as do -eil adjectives (pareil → pareille) and a few exceptions like gentil → gentille and nul → nulle.

gentil / gentille kind
nul / nulle useless, hopeless
pareil / pareille same, similar
vermeil / vermeille vermilion, bright red