act up

1 of 2

verb

acted up; acting up; acts up

intransitive verb

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
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

ACT UP

2 of 2

abbreviation

AIDS Coalition to Unleash Power

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
Verb
That shank was a shocker, and perhaps more concerning was Woods saying his back was acting up int the final hour, leading to the shank. Doug Ferguson, USA TODAY, 16 Feb. 2024 Hopefully no one’s acting up on the group vacation. Steph Koyfman, Condé Nast Traveler, 26 Jan. 2024 The instrument’s dust cover has been acting up since January 6. Amanda Kooser, Forbes, 14 Feb. 2024 Soon after her descent, the walls of the cave grow so wet that the Wi-Fi router begins to act up. D. T. Max, The New Yorker, 21 Jan. 2024 Latin act up for songwriter of the year at the 2024 awards. Thania Garcia, Variety, 19 Dec. 2023 Conexión Divina — Ashlee Valenzuela, Sandra Calixto and Liz Trujillo — are the only música Mexicana act up for best new artist. Thania Garcia, Variety, 14 Nov. 2023 After lunch, Streisand was ready to relax and needed to stretch her back, which lately has been acting up. Wesley Morris, New York Times, 7 Nov. 2023 Three out of the five acts up for artist of the year at the 2023 Billboard Latin Music Awards are Mexican music heavy hitters, a reflection of the genre’s strong hold on Latin music today. Griselda Flores, Billboard, 27 Sep. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'act up.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

Verb

1879, in the meaning defined at sense 1

Time Traveler
The first known use of act up was in 1879

Dictionary Entries Near act up

Cite this Entry

“Act up.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/act%20up. Accessed 19 Mar. 2024.

Kids Definition

act up

verb
: to act in an unruly, abnormal, or annoying way
Last Updated: - Updated example sentences
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