Most adjectives just add -e for a feminine noun, but several common families change more: -il becomes -ille (gentil, gentille), -if becomes -ive (sportif, sportive), -eux becomes -euse (sérieux, sérieuse) and bon becomes bonne. The feminine ending is often the only place you HEAR the difference.
Examples
- Mon frère est très gentil.
- My brother is very kind.
- Ma sœur est gentille aussi.
- My sister is kind too.
- Elle est sportive et sérieuse.
- She is sporty and serious.
The mistake to avoid
Do not just add -e to these: "sportife" and "sérieuxe" do not exist.
Where this fits in
Family & people, French A1: Talk about your family, say what people are like and how old they are, and introduce your friends.