acted up; acting up; acts 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
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Examples of act up in a Sentence
Verb
the two-year-old was acting up in church so much that her dad had to take her outside
you should have seen the boys acting up when they put on their aprons
Recent Examples on the Web
Danielle Sinay, Glamour, 28 May 2025
For the first time, Tindall had to act up without his partner over these past two weeks, with Graeme Jones, his fellow assistant, deputising alongside him.
—Chris Waugh, New York Times, 25 Apr. 2025
Is his palm injury acting up again, or the pressure to join the elite company of Jack Nicklaus, who won 3 times at The PLAYERS Championship?
—Mark Davis, Newsweek, 16 Mar. 2025
Clarke Schmidt’s back acted up, and then his shoulder.
—Brendan Kuty, The Athletic, 25 Mar. 2025
See All Example Sentences for act up
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Verb
Floral and spicy notes bring to mind a meadow in full bloom (without making your allergies act up, thankfully).
—Danielle Sinay, Glamour, 28 May 2025
For the first time, Tindall had to act up without his partner over these past two weeks, with Graeme Jones, his fellow assistant, deputising alongside him.
—Chris Waugh, New York Times, 25 Apr. 2025
Is his palm injury acting up again, or the pressure to join the elite company of Jack Nicklaus, who won 3 times at The PLAYERS Championship?
—Mark Davis, Newsweek, 16 Mar. 2025
Clarke Schmidt’s back acted up, and then his shoulder.
—Brendan Kuty, The Athletic, 25 Mar. 2025
See All Example Sentences for act up
Cite this Entry
“Act up.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/act%20up. Accessed 7 Jul. 2025.
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