(especially of a woman's hair, clothes, behaviour) like a boy

youthful

not serious or important; enjoying pleasure (too much)

trivial, silly

not yet fully developed; too soon (because not ready)

young, inexperienced

very childish

babyish

not sensible; foolish

absurd, giddy, foolish

irritable, testy

irritable, testy

having lived a short time; having existed for a short time; still near its beginning; young people; children

immature