[ uh-duhlt, ad-uhlt ]
/ əˈdʌlt, ˈæd ʌlt /
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See synonyms for: adult / adults / adulthood / adultness on Thesaurus.com

a person who is fully grown or developed or of age.
a full-grown animal or plant.
a person who has attained the age of maturity as specified by law.
verb (used without object)
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.


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Should we be using "adulting" instead of the word "adult" these days?

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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) + -tus past participle suffix


Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


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.

Where does adult come from?

The first records of the term adult come from around the 1520s. It comes from the Latin word adultus, meaning “grown.” 

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What are some other forms of adult?

  • adulthood (noun)
  • adultlike (adjective)
  • adultly (adverb)
  • adultness (noun)
  • adulting (adjective, verb)

What are some synonyms for adult?

What are some other forms related to adult?

What are some words that often get used in discussing adult?

How is adult used in real life?

Adult is a very common word used to refer to a fully developed person, animal, or plant. It’s also commonly used to describe something related to adults.


Try using adult!

True or False?

An adult animal is an animal that is not yet fully developed.

How to use adult in a sentence

British Dictionary definitions for adult

/ (ˈædʌlt, əˈdʌlt) /

having reached maturity; fully developed
of or intended for mature peopleadult education
regarded as suitable only for adults, because of being pornographicadult films and magazines
a person who has attained maturity; a grownup
a mature fully grown animal or plant
law a person who has attained the age of legal majority (18 years for most purposes)Compare infant

Derived forms of adult

adulthood, noun

Word Origin for adult

C16: from Latin adultus, from adolēscere to grow up, from alēscere to grow, from alēre to feed, nourish
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012