A young adult is somebody in their late teens or twenties. A young adult living at home.
The phrase also names a whole category of fiction written for that age. A young adult now reaches the old markers of adulthood about a decade later than their grandparents did.
1nounyoung adultSomebody in their late teens or twenties.
“The flat was shared by four young adult tenants.”
young adult is a person.
Practised in Babies & Growing Up