act up
act up
act up [ phrasal verb ]
1 : to behave badly : to act in a way that is not polite or acceptable
The kids are acting up [=misbehaving] again.
The book gives advice to parents whose children act up.
2 of a machine : to not work properly
The camera started acting up [=malfunctioning] after I dropped it.
3 of a disease : to become worse and to start causing pain or physical problems
His asthma acts up when it's cold outside.
Whenever it rains, my arthritis starts acting up.
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Main Entry: act
