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 noun
adultly
ə-ˈdəlt-lē How to pronounce adult (audio)
ˈa-ˌdəlt-
adverb
adultness
ə-ˈdəlt-nəs How to pronounce adult (audio)
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 adjective

adult

3 of 3

verb

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

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
At first, the dynamic seems ambiguous: closer to that between a mom and her barely adult son than a wife and her husband. Michael O'Sullivan, Washington Post, 15 Nov. 2023 Over a period of more than 2,500 hours of observation at three sites – Southeast Farallon Island, Año Nuevo Island and Tomales Point – scientists identified nearly 300 adult and sub-adult individual great whites. Julia Musto, Fox News, 26 May 2021
Noun
Many more adults got the flu shot with nearly half of the adult population getting one last season, according to the CDC, a number that was slightly higher than the year before. Jen Christensen, CNN, 10 June 2024 Arvada Police wrote in a post on X (formerly Twitter) that the victims are two adults and two children. Charlotte Phillipp, Peoplemag, 10 June 2024
Verb
Hummels compares these definitions to stages or transitions in life: child to adult to senior citizen. Avery Hurt, Discover Magazine, 12 Feb. 2024 Sixty years ago adults Murphy’s age were alarmed by the arrival, haircuts and songs of the Beatles. Kevin Rennie, Hartford Courant, 6 Jan. 2024 See all Example Sentences for adult 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'adult.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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

Time Traveler
The first known use of adult was in 1531

Dictionary Entries Near adult

Cite this Entry

“Adult.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/adult. Accessed 22 Jun. 2024.

Kids Definition

adult

1 of 2 adjective
1
: fully developed and mature
2
: of, relating to, or characteristic of adults
adulthood noun
adultness
ə-ˈdəlt-nəs How to pronounce adult (audio)
ˈad-ˌəlt-
noun

adult

2 of 2 noun
: a fully grown person, animal, or plant
adultlike adjective
Etymology

Adjective

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

Medical Definition

adult

1 of 2 adjective
: 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

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