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Synonyms

act up

British  

verb

  1. informal (intr, adverb) to behave in a troublesome way

    the engine began to act up when we were miles from anywhere

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

act up Idioms  
  1. Misbehave. For example, With an inexperienced rider, this horse always acts up . [c. 1900]

  2. Malfunction, as in I'm not sure what's wrong with my car, but the transmission is acting up . In both usages up means “abnormally.”


Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

“That’s not the idea. The idea is to have them clean their act up so that they do better and the stock goes up and their dividends go up,” Ryan said.

From Seattle Times • Feb. 26, 2024

In her four-star review Midgley suggested the show occasionally "feels scripted", noting the Furys know that "the cameras are on them and perhaps act up for them".

From BBC • Aug. 18, 2023

“You ain’t stoppin’ what’s goin’ on with me sweetheart,” Palmer lip-synced.“So if you gon’ act up, I’m ’bouta link up, I’m ’bouta link up, I’m ’bouta link up.”

From Los Angeles Times • Aug. 16, 2023

My granddaughters get upset, act up and give her a hard time, and I can understand why.

From Washington Post • Aug. 31, 2022

As we settled into our seats for a late-night flight to Paris, my stomach began to act up.

From "Mountains Beyond Mountains" by Tracy Kidder and Michael French

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