Definition of adult in US English:



  • 1A person who is fully grown or developed.

    ‘children should be accompanied by an adult’
    • ‘As the surviving children grow up into adults, we must feel eternally grateful that they are here.’
    • ‘Who knew a large powered wheelchair with two 80 watt batteries and a fully grown adult could do so much damage?’
    • ‘In particular, low birthweight infants who grew to be heavy adults were at high risk of coronary heart disease.’
    • ‘I was a chubby kid who grew into an overweight adult.’
    • ‘Children who are overweight tend to grow up into adults who are overweight.’
    • ‘How can something so small require the undivided attention of two grown adults and still not be satisfied?’
    • ‘I had lost my best friend, the girl I had grown into an adult with.’
    • ‘He hoped to spoil the youngsters and watch them grow up to become adults he could be proud of.’
    • ‘The years passed as the children grew into adults, left home and came home again when on holidays.’
    • ‘There is growing evidence that most adults with moderate coeliac disease can eat oats.’
    • ‘We share hopes and dreams for our kids and expect that we will be able to provide for them as they grow into adults.’
    • ‘Sometimes a young adult who has grown up in a sheltered, relatively conservative environment finds him or herself ready to rebel the moment he or she leaves home.’
    • ‘Would it be better to treat children like adults while they are growing up?’
    • ‘Tickets are £5 for adults and £1 for children accompanied by an adult.’
    • ‘The investment looked canny as the market for gadgets and toys aimed at adults keeps growing.’
    • ‘Other children grow into young adults while in foster care and leave to live independently.’
    • ‘It's about two youths and the evolution of their relationship as they grow into adults.’
    • ‘It is a bit ironic how all little girls want to do is grow up and all adults want to do is be young again.’
    • ‘It allows the child to grow into an adult who feels valued and competent, who can be emotionally attached to others and has empathy for them.’
    • ‘I believe we have to treat grown ups as adults, and everyone has to be free to make his or her own choices.’
    grown person, grown man, grown woman, grown-up person, grown-up, mature person, mature man, mature woman, person of mature age
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    1. 1.1 A fully developed animal.
      • ‘They will kill the caterpillar before it becomes an egg-laying adult.’
      • ‘Codling moth adults were observed on several occasions resting on the plastic egg traps.’
      • ‘John White invented a device, using a laser, to knock out just one cell in a worm, either in a developing animal or an adult.’
      • ‘Two adult bull elephant from the Kruger National Park were released into Addo on the same day, which will provide a much-needed injection into the small gene pool at Addo.’
      • ‘Many people opt to buy a cuddly little puppy instead of an adult.’
      • ‘I can recall looking at the preserved reproductive tracts of several hundred Victorian foxes and noting that few adult, first-year animals had produced young.’
      • ‘This measurement is predictive of a healthier insect and an adult with higher egg-producing capacity.’
      • ‘The four adult and two baby animals will travel down from their home in the Cairngorm mountains of Scotland to pull the sledge, laden with toys, around town.’
      • ‘Fifty feet below the larva, an adult of the same species creeps across the rocky seafloor in search of a meal.’
      • ‘And now, just a few years ago, Mandell returned to the wolves as a fully grown wolf adult.’
      • ‘One adult and a calf have since died and there are still two resident adults and a calf.’
      • ‘One of the animals was a puppy, but the others were adults, and three were bitches in season.’
      • ‘In some ways training a puppy is easier than training an adult or adolescent dog.’
      • ‘The latter possibility is very unlikely, as the animal was an adult.’
      • ‘But these were mouse cells, not human cells, and came from an embryo, not an adult.’
      • ‘The insect life cycle is ended before it becomes a biting, breeding, egg-laying adult that plagues your pets.’
      • ‘The flies appeared to be normal, but they could not smell at all, either as larvae or as adults.’
      • ‘After the wasp adult emerges inside the aphid mummy, it cuts a circular hole to exit.’
      • ‘In July, the adult emerges from the pupa and pushes its way to the soil surface.’
      • ‘Not far from Clitheroe I watched an adult and three young birds twisting and turning in the air like skilful pilots doing aerobatics.’
    2. 1.2Law A person who has reached the age of majority.
      See majority (sense 2)
      • ‘The judgements for adults and children are treated separately in the assessment framework.’
      • ‘It also discussed the current position, whereby the consent of an adult with parental responsibility will be valid even when the child is able to give a valid consent but refuses to do so.’
      • ‘Were he an adult with a criminal record, it is almost certain he would face a significant period of imprisonment.’
      • ‘The Appellant is now a young adult of 20 years of age.’
      • ‘These provisions, when first enacted, applied to both adults and children.’


  • 1(of a person or animal) fully grown or developed.

    ‘the adult inhabitants of the U.S’
    • ‘The adult guinea-pig can grow to as much as 30 centimetres in length and 1200 grams in weight.’
    • ‘When it falls off naturally, the adult tooth grows into the gap.’
    • ‘With such a reliable food source, the adult populations can grow well above what would normally be possible, putting additional pressure on the ecosystem.’
    • ‘Tissue and organs grown from adult stem cells would not be subject to the same rejection problems because they would be genetically identical to the cell donor.’
    • ‘She grew a full set of baby teeth, lost them and grew a set of adult teeth in all that time.’
    • ‘Most animals are developmentally programmed to grow to a characteristic adult size.’
    • ‘The duck is growing his adult feathers and when I go out to feed him in the morning, he makes a terrible racket when I take his bowl away from him to fill it up.’
    • ‘As the organizations sponsored an increasing number of dances, the number of youth and adult bands quickly grew.’
    • ‘This audio book provides guidelines for every stage in the puppy raising process from adopting your puppy to watching them grow into healthy adult dogs.’
    • ‘It was a very great privilege to have been on such intimate terms with a wild creature, to have acted in loco parentis and watched him grow into a handsome adult bird.’
    • ‘Now that Halloween has become a fully adult holiday, it is only fitting that we track down the essentials you'll need over this Halloween weekend.’
    • ‘Hair grows quickest in young adult women 16 to 24 years old.’
    • ‘We must also help them to grow up and face adult responsibilities.’
    • ‘School bullies usually grow up to be adult bullies, so bullies need to be given zero tolerance.’
    • ‘It is assumed, in these contexts, that normal, fully developed adult human beings are responsible beings.’
    • ‘There are many adult gamers that grew up with Nintendo and still want to connect with the company that they associated so strongly with video gaming in their youth.’
    • ‘In the 10 years since then, children's fare has grown more sophisticated and adult expectations have diminished, creating a space in the middle where they can all meet.’
    • ‘The movie pay-per-view business may have a long way to go before it realizes its full potential, but the adult movie sub-sector is growing by leaps and bounds.’
    • ‘They take about two years to grow to full adult size.’
    • ‘When we were little, he was lanky and awkward - just starting to grow his adult teeth; I was short, bony and shy.’
    mature, grown-up, fully grown, full-grown, fully developed, fully fledged, of age, having reached one's majority
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    1. 1.1 Of or for adult people.
      ‘adult education’
      ‘the responsibilities of adult life’
      • ‘Women also have been well represented in adult basic education courses, many of which are provided at community colleges around the country.’
      • ‘Formal education and training for adult life assumed differing destinies for boys and for girls and for differing levels in society.’
      • ‘The provincial Department of Education is offering adult learners two different exam times this year.’
      • ‘They encourage unity and solidarity among the adult and community education groups in Kildare.’
      • ‘Turning to adult basic education and training exams, the council found there had been an improvement in quality.’
      • ‘With no education or adult help, this is a daunting task.’
      • ‘The two foremost external barriers to adult enrollment in higher education are limited time and limited funds.’
      • ‘The increase will also allow the college to continue offering adult basic education for free, he said.’
      • ‘The children will devise, plan and implement a programme to get adult relatives back into education.’
      • ‘The association hoped to increase awareness of the lack of adult sex education and resources on the subject, Cheng said.’
      • ‘It also offers adult basic education and English for Speakers of Other Languages courses.’
      • ‘There is a lack of good evidence of effectiveness of safety education for adult pedestrians, specially elderly people.’
      • ‘And the manner in which we are adapting to our new multicultural society is now a major issue facing adult learners an education conference in Ennis was also told yesterday.’
      • ‘The school wishes to plan for the future and to respond to the needs of the community in regard to adult and continuing education.’
      • ‘Implications in this situation might be the exploration of the possibilities for a joint union/management adult basic education program.’
      • ‘Consider your personal financial situation; you start your adult life with some education and usually not much else.’
      • ‘It will be conducted by Fr. Todd Nolan who is in charge of adult religious education in the diocese.’
      • ‘Giving help towards adult and second chance education also forms part of our programme of assistance.’
      • ‘At the same time, many contemporary Episcopal congregations clamor for more and more in-depth adult - education offerings.’
      • ‘Teenage mothers often face daunting obstacles to completing their education and achieving adult independence.’
    2. 1.2 Emotionally and mentally mature.
      ‘an effort to be adult and civilized’
      • ‘‘He is determined to turn his life around and deal with matters in a more responsible, mature and adult way,’ Mr Jones said.’
      • ‘And he should be adult enough and mature enough and experienced enough to understand it.’
      • ‘So when you get something that is for a mature adult audience, it's sort of a relief.’
      • ‘On some rare occasions, Andrew would take his younger brother along for an adventure that to Aaron seemed very adult and mature.’
      • ‘This year they felt that the two young fellows got along very well and they felt that the older child was adult enough or mature enough to adequately supervise the boy.’
      • ‘Mature, adult comprehension can lead us all to see that there are some very intelligent and worthy of praise men out there.’
      • ‘He's resolutely adult, more mature and perhaps more cautious of the world.’
      • ‘Her idealization of her mate results in a one-sided relationship that doesn't seem to function on any mature, adult level.’
      • ‘It's a very mature, adult role, which to me, is what Norman is really like in person.’
      • ‘There was something definitely more adult and mature about her best friend and for a moment, a feeling of intense resentment welled up within her.’
      • ‘A better man than me might have talked to her about it, might have resolved it in a mature, adult fashion.’
    3. 1.3 Sexually explicit or pornographic (used euphemistically to refer to a movie, book, or magazine).
      • ‘The accounts will confirm the sale in March of Desmond's adult magazine stable.’
      • ‘We also assessed the availability of products that could be used as educational or therapeutic products, such as adult magazines, books, and videos.’
      • ‘Somehow, George managed to interest the people who published Penthouse Magazine in a line of adult comic books produced on a handsome budget.’
      • ‘It used to be that the studio producing an adult film would carry that information at their studio.’
      • ‘They had one initially and the idea was that it would denote adult films that weren't in the realm of sex and exploitation.’
      • ‘It turned out the lawyers were referring to dozens of adult magazines seized from his home.’
      • ‘How many adult films, bookstores, magazines, or websites will remain for you to enjoy when such a law is enforced?’
      • ‘A former marine from Detroit, he had wanted to be a policeman, but instead drifted into adult films in the mid-Nineties.’
      • ‘A couple of adult film producers based in California are being prosecuted in Pittsburgh by U.S. Attorney Mary Beth Buchanan.’
      • ‘He points out that mainstream films will only be given a rating such as PG or R, but will not be subject to approval by the board like adult sex films are.’
      • ‘They said they were interested in getting me involved in the adult film industry.’
      • ‘The sunglasses must not merely be chosen, they must be selected in a process at least as involved as that of an eighteen-year-old selecting his first adult film at the local video shop.’
      • ‘This X-rated adult book concerns the battle between good and evil.’
      • ‘A lot of people derive enjoyment from watching adult films.’
      • ‘Well, not unless you are considering a career in the adult film industry, then I suppose it's perfectly acceptable course of action.’
      • ‘The shop has been operating for more than three months, selling lingerie, adult toys and adult magazines, none of which requires a licence.’
      • ‘Dietz and Sears examined books, magazines, and films in adult bookstores in four cities.’
      • ‘It's not really an adult film, even though it has some slight sexual references, and some scenes involving drugs.’
      • ‘According to Hotel Secrets, 60 percent of in-room entertainment revenue comes from adult films.’
      sexually explicit, obscene, pornographic, hard-core, soft-core, lewd, smutty, dirty, filthy, vulgar, crude, rude, racy, risqué, ribald, naughty, arousing, earthy, rabelaisian, erotic, carnal, sensual, sexy, suggestive, titillating, spicy, raw, taboo, off colour, indecent, improper
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[no object]informal
  • Behave in a way characteristic of a responsible adult, especially by accomplishing mundane but necessary tasks.

    ‘I've adulted with moderate success this week by compiling invoices and billing my client’
    ‘I am 24 and still trying to figure out how to adult’


Mid 16th century: from Latin adultus, past participle of adolescere ‘grow to maturity’ (see adolescent).