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act up

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verb
(intr, adverb) informal to behave in a troublesome waythe engine began to act up when we were miles from anywhere
QUIZ
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Question 1 of 7
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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

How to use act up in a sentence

Other Idioms and Phrases with act up

act up

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.”

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
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