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act up

Definition of act up in English:

1(Of a thing) fail to function properly: the plane’s engine was acting up
More example sentences
  • The laptop computer that we have been using for performing pulmonary function tests had been acting up lately, overheating and shutting itself off.
  • Then again, my body did like to pick the wrong times to start acting up.
  • I think the service is messed up here, it was acting up before the phone broke.
malfunction, go wrong, be defective, be faulty
informal be on the blink, be on the fritz
1.1(Of a person) misbehave.
misbehave, behave badly, be up to mischief, become unruly
See parent entry: act

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Word of the day fortissimo
Pronunciation: fôrˈtisəˌmō
(especially as a direction) very loud or loudly