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
James Horncastle, New York Times, 2 July 2025
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
See All Example Sentences for act up
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Verb
His calf was acting up and a decision was taken last Thursday for him and Inter’s other players with niggling injuries — Yann Bisseck, Piotr Zielinski and Benjamin Pavard — to leave the Club World Cup early.
—James Horncastle, New York Times, 2 July 2025
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
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 18 Jul. 2025.
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