Adult
mid 16th century: from Latin adultus, past participle of adolescere ‘grow to maturity’ (see adolescent).
wiktionary
From French adulte, Latin adultus(“grown up”), perfect passive participle of adolescō(“I grow up”). Compare adolescent.
etymonline
adult (adj.)
1530s (but not common until mid-17c.) "grown, mature," from Latin adultus "grown up, mature, adult, ripe," past participle of adolescere "grow up, come to maturity, ripen," from ad "to" (see ad-) + alescere "be nourished," hence, "increase, grow up," inchoative of alere "to nourish," from a suffixed form of PIE root *al- (2) "to grow, nourish."
Meaning "mature in attitude or outlook" is from 1929. As a euphemism for "pornographic," it dates to 1958 and does no honor to the word. In the old British film-rating system, A indicated "suitable for exhibit to adult audiences," and thus, implicitly, unsuitable for children (1914).
adult (n.)
"adult person," 1650s, from adult (adj.).
