Webster's Revised Unabridged Dictionary · 1913

Adult

Adult ({not transcribed}) , adjective

[Latin adultus, past participle of adolescere, akin to alere to nourish: compare French adulte. See Adolescent, Old.]

Having arrived at maturity, or to full size and strength; matured; as, an adult person or plant; an adult ape; an adult age.

Adult , noun

A person, animal, or plant grown to full size and strength; one who has reached maturity.

In the common law, the term is applied to a person who has attained full age or legal majority; in the civil law, to males after the age of fourteen, and to females after twelve.