adult

1 of 4

adjective

ə-ˈdəlt  ˈa-ˌdəlt 

1

: fully developed and mature : grown-up

an adult lion

2

: of, relating to, intended for, or befitting adults

an adult approach to a problem

3

: dealing in or with explicitly sexual material

adult bookstores

adult movies

adulthood

ə-ˈdəlt-ˌhu̇d 

noun

adultly

ə-ˈdəlt-lē 

ˈa-ˌdəlt-

adverb

adultness

ə-ˈdəlt-nəs 

ˈa-ˌdəlt-

noun

adult

2 of 4

noun (1)

: one that is adult

especially : a human being after an age (such as 21) specified by law

adultlike

ə-ˈdəlt-ˌlīk 

adjective

adult

3 of 4

verb

ə-ˈdəlt 

adulted; adulting; adults

intransitive verb

1

informal : to behave like an adult : to attend to the ordinary tasks required of a responsible adult

Do we really have to adult today?

—Lauren Merola

Stop complaining that you have to adult today. Being an adult is awesome.

—Suzanne Lucas

Learning how to "adult" is a necessity for these college freshmen in order to figure out new medication schedules and if their parents' insurance will cover impromptu ER visits.

—Meredith Newman

2

informal : to become an adult

It could be something small, like bailing on your friends at the last second. Or something bigger, like not showing up for work. Whatever the case may be, it's a sign you haven't fully "adulted" if you constantly slack off on your responsibilities.

—Carolyn Steber

But there is one real benefit to growing older and adulting: We essentially get to do whatever we want to do.

—Sharon Pope

adultness

4 of 4

noun (2)

adult·​ness ə-ˈdəlt-nəs  ˈa-ˌdəlt- 

plural -es

: the quality or state of being adult

especially : intellectual maturity usually associated with an adult

an adultness in the quality of his dialogue

—R. A. Cordell

Synonyms of adult

Adjective

• mature

Noun (1)

• grown-up
• elder

Examples of adult in a Sentence

Adjective

preparing children for adult life

We need to approach this in an adult way.

Noun (1)

Her books appeal both to children and to adults.

Children must be accompanied by an adult in the museum.

Only adults can purchase alcohol.

This film is for adults only. Minors are not admitted.

People who are close friends as children aren't always friends as adults.

studying interactions between young birds and adults

Recent Examples on the Web

Adjective

Males dusky sharks can grow up to 14 feet, which is about the size of a sub-adult white shark, according to Chapman. — Julia Jacobo, ABC News, 1 June 2026

The junior car had gotten seriously adult. — Robert Ross, Robb Report, 28 Oct. 2025

Noun

Older adults, young children and people with heart or kidney conditions face the highest risk. — Hanna Wickes, Sacbee.com, 1 July 2026

Most adults wait an average of nine years after first noticing hearing loss before seeking treatment. — Allison Palmer, Fort Worth Star-Telegram, 1 July 2026

Verb

Varsha’s eyes are blazing, not with frustration or peevishness, which would not have been untoward in a child of her age, but with an anger that seems almost adult in its intensity. — Literary Hub, 16 June 2026

The main trails are designed for ages 7 to adult and there is an Adventure Playground with low-to-the-ground experiences for ages 3 to 6. — Staff Report, Hartford Courant, 21 Feb. 2026

Word History

Etymology

Adjective

borrowed from French & Latin; French adulte, going back to Middle French, borrowed from Latin adultus, from past participle of adolēscere, adulēscere "to become mature, grow up," from ad- ad- + alēscere "to be nourished, grow up," probably inchoative derivative of *alēre "to grow," stative derivative of alere "to nurse, feed, nourish" — more at old entry 1

Noun (1)

derivative of adult entry 1

First Known Use

Adjective

1531, in the meaning defined at sense 1

Noun (1)

1655, in the meaning defined above

Verb

1909, in the meaning defined at sense 2

Noun (2)

1663, in the meaning defined above

Phrases Containing adult

• adult alternative
• adult education
• adult life
• adult-onset diabetes
• adult respiratory distress syndrome
• consenting adult
• pre-adult
• young adult

Rhymes for adult

• consult
• exult
• insult
• occult
• result
• catapult
• subadult
• cult

Kids Definition

adult

1 of 2 adjective

ə-ˈdəlt  ˈad-ˌəlt 

1

: fully developed and mature

2

: of, relating to, or characteristic of adults

adulthood

ə-ˈdəlt-ˌhu̇d 

noun

adultness

ə-ˈdəlt-nəs 

ˈad-ˌəlt-

noun

adult

2 of 2 noun

: a fully grown person, animal, or plant

adultlike

ə-ˈdəlt-ˌlīk 

adjective

Etymology

Adjective

from Latin adultus "having grown up," from adolescere "to grow up" — related to adolescence

Medical Definition

adult

1 of 2 adjective

ə-ˈdəlt  ˈad-ˌəlt 

: fully developed and mature

adult

2 of 2 noun

1

: one that has arrived at full development or maturity especially in size, strength, or intellectual capacity

2

: a human male or female after a specific age (as 18 or 21)

Legal Definition

adult

noun

: a person who has reached an age specified by law compare child, infant, minor