grown-up (manner, etc.); mature; adult
彼女は年の割に大人っぽい。
She seems mature for her age.
この服は少し大人っぽくて娘には似合わない。
These clothes look a bit too grown-up for my daughter.
髪型を変えたら急に大人っぽかった。
With the new hairstyle she suddenly looked grown-up.