adult
「大人」 has other readings with different meanings.
adult; grown-up
person of virtue; great person; magnanimous person
child (esp. one of elementary school age or younger)
child in elementary or middle school
大人の入場料はいくら?
How much is the adult admission?
大人になったら何をしたいですか。
What do you want to do when you grow up?
この映画は大人しか見られない作品ですよ。
This movie is a film that only adults can watch.