French Adjectives Ending in -x

French adjectives ending in -x are unchanged in the masculine plural — no extra -s is added: doux → doux, faux → faux. The feminine replaces -x with a different ending: doux → douce, faux → fausse, jaloux → jalouse.

doux / douce
doux / douces
soft, sweet, gentle
faux / fausse
faux / fausses
false
jaloux / jalouse
jaloux / jalouses
jealous
roux / rousse
roux / rousses
red-haired