adulthood

UK: /ˈædʌlthʊd/

WordReference Random House Learner's Dictionary of American English © 2026

a•dult /əˈdʌlt, ˈædʌlt/   n. [countable]

1. Developmental Biology a person who is fully grown, developed, or of age:
   Only adults may purchase alcohol.

adj.  [usually: before a noun]

2. Developmental Biology having attained full size and strength;
   mature:
   adult plants.
3. intended only for adults;
   not suitable for children:
   adult movies.
4. of or like a fully grown, mature person:
   The teenager had a very adult expression on her face.

a•dult•hood, n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2026

a•dult  (ə dult′, ad′ult), adj. 

1. having attained full size and strength;
   grown up;
   mature:
   an adult person, animal, or plant.
2. of, pertaining to, or befitting adults.
3. intended for adults;
   not suitable for children:
   adult entertainment.

n. 

4. a person who is fully grown or developed or of age.
5. a full-grown animal or plant.
6. Lawmaking a person who has attained the age of maturity as specified by law.

• Latin adultus grown (past participle of adolēre to make grow), equivalent. to ad- ad- + ul- (identical with base al- in aliment, ol- in prolific) + -tus past participle suffix
• 1525–35; 1925–30 for def. 3;

a•dult′hood, n. 
a•dult′like′, adj. 
a•dult′ly, adv. 
a•dult′ness, n.