Definition of adult adjective from the Oxford Advanced American Dictionary

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adult

adjective
/əˈdʌlt; ˈædʌlt/
 
 
1 fully grown or developedpreparing young people for adult lifethe adult populationadult monkeys2 behaving in an intelligent and responsible way; typical of what is expected of an adult synonym grown-up1When my parents split up, it was all very adult and open.3 [only before noun] intended for adults only, because it is about sex or contains violencean adult movie see also adulthood