Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun grownup

1 sense of grownup

Sense 1
adult, grownup -- (a fully developed person from maturity onward)
       => person, individual, someone, somebody, mortal, soul -- (a human being; "there was too much for one person to do")

Antonyms of adj grownup

1 sense of grownup

Sense 1
adult, big, full-grown, fully grown, grown, grownup -- ((of animals) fully developed; "an adult animal"; "a grown woman")

INDIRECT (VIA mature) -> immature -- (not yet mature)

Similarity of adj grownup

1 sense of grownup

Sense 1
adult, big, full-grown, fully grown, grown, grownup -- ((of animals) fully developed; "an adult animal"; "a grown woman")
       => mature (vs. immature) -- (having reached full natural growth or development; "a mature cell")