act up

1 of 2


acted up; acting up; acts up

intransitive verb

: to act in a way different from that which is normal or expected: such as
: to behave in an unruly, recalcitrant, or capricious manner
the children were acting up
: to function improperly
this typewriter is acting up again
: to become active or acute after being quiescent
her rheumatism started to act up


2 of 2


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
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 The House of Representatives was pitching another fit, with balky Republicans acting up, must-pass legislation stalled and restless lawmakers anxiously eyeing the exits. Mark Z. Barabak, Los Angeles Times, 27 Aug. 2023 And McCarthy leaned in heavily to President Donald Trump as the 2020 election approached, and whenever some Republican acted up, very few faced any real punishment. Democrat-Gazette Staff and Wire Reports, Arkansas Online, 30 July 2023 See More

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


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.” Dictionary, Merriam-Webster, Accessed 24 Feb. 2024.

Kids Definition

act up

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