grown-up

• grownup, grown up

grown-up (comparative more grown-up, superlative most grown-up)

1. Adult, physically mature.

   Synonyms: see Thesaurus:adultlike, Thesaurus:full-grown

2. Of, pertaining to, or suitable for adults.

   Synonyms: mature; see also Thesaurus:for adults

3. Having a mature outlook.

   Synonyms: adultish; see also Thesaurus:mature

grown-up (plural grown-ups)

1. (often childish) An adult.
   • 1909, Archibald Marshall [pseudonym; Arthur Hammond Marshall], “A Court Ball”, in The Squire’s Daughter, New York, N.Y.: Dodd, Mead and Company, published 1919, →OCLC, page 9:

     They stayed together during three dances, went out on to the terrace, explored wherever they were permitted to explore, paid two visits to the buffet, and enjoyed themselves much in the same way as if they had been school-children surreptitiously breaking loose from an assembly of grown-ups.

   • 1988 June 8, Bill Watterson, Calvin & Hobbes (comic):

     Do you think the grown-ups will have the world fixed up by the time they hand it over to us?

   • 2006 August 9, Randall Munroe, “Grownups”, in xkcd‎ (webcomic):

     Because we're grown-ups now, and it's our turn to decide what that means.

• Compact Oxford English Dictionary
• American Heritage Dictionary

• upgrown