Adult A*dult", a. [L. adultus, p. p. of adolescere, akin to alere to nourish: cf. F. 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 A*dult", n. A person, animal, or plant grown to full size and strength; one who has reached maturity. Note: 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.