adult

Etymology

From French adulte, from Latin adultus (“grown up”), perfect passive participle of adolescō (“I grow up”). Compare adolescent.

noun

1. A fully grown human or animal.
   The young not only differs from the adult by the presence of its gills, but its feet are only developed by degrees, and in several genera there are also a deciduous beak and tail, and intestines of a different form 1840, Georges Cuvier, Edward Blyth, Robert Mudie, George Johnston, J.O. Westwood, “The fourth order of reptiles—The batrachians”, in Cuvier's Animal Kingdom, page 286
2. A person who has reached the legal age of majority.

adj

1. Fully grown.
   an adult human, animal, or plant
   The paws of the adult brown bear, and also their hams, especially when smoked, are considered a great delicacy. 1837, Michael Donovan, Domestic Economy: Human Food, Animal and Vegetable, page 86
2. Intended for or restricted to adults rather than children due to size, maturity, knowledge level, judgement, etc.
   1. Containing situations or discussions intended primarily for adults, such as serious crime, illicit drug use, extramarital affairs, etc.
      adult situations; adult discussions
   2. (of a beverage) Containing alcohol, intended for consumption only by adults.
      an adult drink; an adult root beer float
   3. (of a cookie, gummy, etc.) Containing marijuana, intended for consumption only by adults.
      an adult cookie; adult gummy worms
   4. Containing material of an explicit sexual nature; of, or pertaining to, pornography.
      an adult movie
      This program contains adult content. Parental discretion is advised.
   5. Containing excessive vulgar or profane speech, text or images, intended only for adults.
      adult language; an adult cartoon

verb

1. (intransitive, informal) To behave like an adult.
2. (nonstandard, rare) To (cause to) be or become an adult.
   Womanhood was achieved at twenty-one, when the female was "adulted"; manhood was fully achieved at twenty-five, […] 1974, Occasional Papers, numbers 42-46, Syracuse University, page 5
   The process of adulting children[…] overlaps with the process of the uncontrolled infiltration of the media[…] into children’s imagination. 2013, Ewa Rewers, The Contradictions of Urban Art, page 84