act up

verb

Definition of act up

1 : to act in a way different from that which is normal or expected: such as
a : to behave in an unruly, recalcitrant, or capricious manner
  • the children were acting up
b : show off
c : to function improperly
  • this typewriter is acting up again
2 : to become active or acute after being quiescent
  • her rheumatism started to act up

Examples of act up in a Sentence

  1. the two-year-old was acting up in church so much that her dad had to take her outside

  2. you should have seen the boys acting up when they put on their aprons

First Known Use of act up

1879

in the meaning defined at sense 1

See Words from the same year
NEW! Time Traveler

ACT UP

abbreviation

Definition of ACT UP

AIDS Coalition to Unleash Power


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