C2disapprovingnot behaving in a way that is as calm and wise as people expect from someone of your age: Stop being so silly and immature, Ben!She's rather immature for her age, don't you think?Physically and mentally mature and immature›disapprovingnot having much experience of something: politically immaturePhysically and mentally mature and immature›specializednot yet completely grown or developed: While the animals are still immature, they do not breed.Physically and mentally mature and immatureimmaturity
/-ˈtʃʊə.rɪ.ti//-ˈtʊr.ə.t̬i/noun[U]Physically and mentally mature and immature