adult

American  

[uh-duhlt, ad-uhlt] / əˈdʌlt, ˈæd ʌlt /

noun

• adults
  plural

1. a person who is fully grown or developed or of age.

2. a full-grown animal or plant.

3. a person who has attained the age of maturity as specified by law.

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adjective

1. having attained full size and strength; grown up; mature.

   an adult person, animal, or plant.

2. of, relating to, or befitting adults.

3. intended for adults; not suitable for children.

   adult entertainment.

verb (used without object)

1. Informal. (of a young person) to do things and assume responsibilities that are associated with being an adult; act like an adult (usually used facetiously about minor accomplishments).

   I cook dinner for myself most nights—guess that means I'm adulting.

adult British  

/ ˈædʌlt, əˈdʌlt /

adjective

1. having reached maturity; fully developed

2. of or intended for mature people

   adult education

3. regarded as suitable only for adults, because of being pornographic

   adult films and magazines

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noun

1. a person who has attained maturity; a grownup

2. a mature fully grown animal or plant

3. law a person who has attained the age of legal majority (18 years for most purposes) Compare infant

Usage

What does adult mean? An adult is a person who is fully grown or developed. This could refer to a person’s body being done growing or their mind being fully developed. An adult child is someone’s child who is fully grown, as in Murray’s adult children are all married and have children of their own. An adult is also a person who has reached an age that their society says allows them responsibilities and benefits not allowed to children. For example, in the United States someone who is 18 years old is in many cases considered an adult. Eighteen-year-olds can vote, sign a contract, join the military, and other actions children are not allowed to do. An adult can also be a fully grown or matured plant or animal, as in Once my puppy becomes an adult, I’ll need to get them a bigger crate. Adult can also be used to describe something related to adults or adulthood, such as adult responsibilities—like paying rent. Adult can also be used to describe something not suitable for children. Things labeled as adult entertainment, for example, often include explicit sexual content. Informally, adult can be used as a verb meaning to take on responsibilities usually reserved for adults, such as owning a house. It’s often used humorously to describe small responsibilities, as in Tanya really adulted today by putting away her laundry.

Other Word Forms

Derived Forms

• adulthood
  noun
• adultness
  noun
• subadultness
  noun
• adultlike
  adjective
• nonadult
  adjective
• quasi-adult
  adjective
• subadult
  adjective
• unadult
  adjective
• adultly
  adverb

Inflected Forms

Nouns

• adults
  plural

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Etymology

Origin of adult

First recorded in 1525–35; from Latin adultus “grown” (past participle of adolēre “to make grow”), equivalent to ad- ad- + ul- (identical with base al- in aliment ( def. ) ) + -tus past participle suffix

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Explanation

Adult is noun and an adjective, both of which refer to something mature, no longer a child. A full-grown person is called an adult: they can vote, rent cars, and choose to eat sugary cereal for dinner every night. If you're still a child, then you are not an adult — that's the noun version. Childish people don't behave in an adult manner — that's the adjective. A child might be scared by the Wicked Witch of the West, but an adult knows she's not real. Learning the difference between real life and make-believe is one of the upsides of becoming an adult.

Example Sentences

See Examples For:

adult adults

Young adult stories come in every imaginable flavor, and flavor combination, and several are present in “Phony,” premiering Tuesday on Hulu.

From Los Angeles Times ● Oct. 19, 2026

That they “understand their own mental health and know that becoming an adult doesn’t mean having to face everything alone.”

From Salon ● Oct. 18, 2026

Transitioning from parenting a child to partnering with a full-grown adult can be difficult.

From The Wall Street Journal ● Oct. 17, 2026

“The world, in my view, is changing faster than at any point in my adult life.”

From MarketWatch ● Oct. 16, 2026

“It’s one thing go off island as an adult, go explore and learn and come back. It’s another thing take a keiki away from this land.”

From "Clairboyance" by Kristiana Kahakauwila

Thirty-seven percent of adults under 30 regularly get news from such online influencers, according to the Pew Research Center.

From The Wall Street Journal ● Oct. 20, 2026

Six in 10 adults believe there’s too much economic inequality, according to a Pew Research Center poll released last week.

From MarketWatch ● Oct. 20, 2026

A June Pew Research Center survey found 71% of U.S. adults expect AI to mean fewer jobs in the U.S. over the next two decades, up from 64% in 2024.

From Los Angeles Times ● Oct. 20, 2026

While younger people have driven the rise in its use, Moore said the last year had seen a rise in referrals for adults aged 25 to 34, particularly in Cardiff and south-east Wales.

From BBC ● Oct. 19, 2026

The three of them proceed to talk about boring stuff like stock markets, coupons, and whatever else adults like gossiping about.

From "Kwame Crashes the Underworld" by Craig Kofi Farmer

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