adult

1 of 3

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 3

noun

: 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 3

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

Synonyms of adult

Adjective

• mature

Noun

• 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

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

While on the ground, the eagle was seen in a fight with two sub-adult eagles, according to the nonprofit. — Assistant Editor, Los Angeles Times, 20 July 2026

The encounter is rare because the vast majority of sub-adult and adult sharks end up at Cape Cod, Dodd said. — Julia Jacobo, ABC News, 7 July 2026

Noun

Many older adults are staying active through walking, jogging or taking yoga and exercise classes. — Nancy Badertscher, AJC.com, 6 Aug. 2026

The new vaccine was found to be about 27% more effective during the 2024–25 respiratory virus season than standard flu shots in Moderna’s study, which enrolled over 40,000 adults 50 and older. — Elise Haulund, CNN Money, 6 Aug. 2026

Verb

While many are still figuring out how to adult, navigating the ins and outs of accessing mental health support can seem overwhelming. — Mark C. Perna, Forbes.com, 28 July 2026

The institution must notify law enforcement or adult protective services. — Kurt Knutsson, FOXNews.com, 17 July 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

derivative of adult entry 1

First Known Use

Adjective

1531, in the meaning defined at sense 1

Noun

1655, in the meaning defined above

Verb

1909, in the meaning defined at sense 2

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