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
Brendan Kuty, The Athletic, 25 Mar. 2025
Mount Spurr, located about 75 miles West of Anchorage, has been acting up in recent weeks, prompting officials at the U.S. Geological Survey and Alaska Volcano Observatory to issue a yellow alert.
—Mary Walrath-Holdridge, USA TODAY, 14 Mar. 2025
The elbows acted up again this past offseason, forcing Stanton to stop swinging a few weeks before reporting to spring training.
—Gary Phillips, New York Daily News, 14 Mar. 2025
The sisters may have spent weeks teasing the first single off their new album through several funny little videos and familiar-looking album art, but the tell-tale sign of new Haim music is when the weather gets good and people feel like acting up.
—Fran Hoepfner, Vulture, 12 Mar. 2025
See All Example Sentences for act up
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Verb
Clarke Schmidt’s back acted up, and then his shoulder.
—Brendan Kuty, The Athletic, 25 Mar. 2025
Mount Spurr, located about 75 miles West of Anchorage, has been acting up in recent weeks, prompting officials at the U.S. Geological Survey and Alaska Volcano Observatory to issue a yellow alert.
—Mary Walrath-Holdridge, USA TODAY, 14 Mar. 2025
The elbows acted up again this past offseason, forcing Stanton to stop swinging a few weeks before reporting to spring training.
—Gary Phillips, New York Daily News, 14 Mar. 2025
The sisters may have spent weeks teasing the first single off their new album through several funny little videos and familiar-looking album art, but the tell-tale sign of new Haim music is when the weather gets good and people feel like acting up.
—Fran Hoepfner, Vulture, 12 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 Apr. 2025.
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