← BackshareGuessfull grown/ˌfʊlˈɡroʊn/adjectiveHaving reached full size and development; no longer young or immature.A full-grown lion can weigh over 400 pounds.The full-grown oak tree towered over the house.She adopted a full-grown cat from the shelter instead of a kitten.SynonymsadultmatureAntonymsimmatureyoung