act up

verb

Definition of act upnext
1
as in to act out
to behave badly the two-year-old was acting up in church so much that her dad had to take her outside

Synonyms & Similar Words

Relevance

Antonyms & Near Antonyms
2
as in to cut up
to engage in attention-getting playful or boisterous behavior you should have seen the boys acting up when they put on their aprons

Synonyms & Similar Words

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Recent Examples of act up Baye continued acting up until 2023. — Kimberlee Speakman, PEOPLE, 18 Apr. 2026 The capsule’s toilet is already acting up. — Marcia Dunn, Chicago Tribune, 2 Apr. 2026 The black flies are not the only troublesome creature acting up during the unseasonably warm weather. — Clara Harter, Los Angeles Times, 28 Mar. 2026 Meanwhile, the guests, who have literally just arrived five minutes ago, are already acting up. — Rafaela Bassili, Vulture, 10 Mar. 2026 See All Example Sentences for act up
Recent Examples of Synonyms for act up
  1. act out
  2. cut up
  3. misconduct
  4. show off
  5. disobey
  6. horse around
  7. carry on
Verb
  • She was thrown right into the mix, acting out a meet-cute with Montana Jordan’s Georgie Cooper that culminated with a kiss.
    — Ryan Coleman, Entertainment Weekly, 26 Oct. 2026
  • With the final credits barely up, Musk is acting out exactly that blueprint.
    — Steven Zeitchik, HollywoodReporter, 22 Oct. 2026
Definition of act out
Verb
  • Californios’ reign began to vanish even before the discovery of gold, when droughts and floods wiped out their easygoing livelihoods, and their lands were cut up, sold off, and their land grants swept aside by the new state.
    — Patt Morrison, Los Angeles Times, 30 Oct. 2026
  • The first plan, which would have cut up to 18 English learner teachers and affected at least two dozen schools, drew backlash.
    — Beret Leone, CBS News, 28 Oct. 2026
Definition of cut up
Verb
  • The Utah Supreme Court ordered a new trial last year, pointing to misconduct by investigators.
    — Landon Mion, FOXNews.com, 30 Sep. 2026
  • In addition, referees were instructed to apply the rules regarding fouls and misconducts more strictly – a move meant to protect players and their inventiveness.
    — Cesar R. Torres, The Conversation, 26 May 2026
Definition of misconduct
Verb
  • Based on the comments on an X post by the Heat showing off the changes, Heat fans seem to approve.
    — Chuck Schilken, Los Angeles Times, 30 Oct. 2026
  • Tennis superstar Serena Williams just updated her look for winter, showing off an icy blond look as her color for the season.
    — Arushi Jacob, Footwear News, 30 Oct. 2026
Definition of show off
Verb
  • One even got in trouble and is shackled to a wooden pillory, serving as an example to others who disobey the crown and engage in piracy.
    — Patrick Connolly, The Orlando Sentinel, 22 Oct. 2026
  • The league fails to react to any of the players who disobey the rules.
    — Joe Kinsey OutKick, FOXNews.com, 20 Oct. 2026
Definition of disobey
Verb
  • Also, don’t get too out of control horsing around with friends in the water.
    — John Natale, Hartford Courant, 16 Aug. 2026
  • According to McGrady, the only royal who didn’t enjoy the time away in the Highlands was the late Princess Diana, who didn’t fit in with the family’s outdoorsy vibes and didn’t enjoy riding horses around the property due to a fall as a child.
    — Meredith Kile, PEOPLE, 12 Aug. 2026
Definition of horse around
Verb
  • At the same time, the city has been marked with a recent burst of violence as some criticize Quiroz for failing to carry on her partner’s fight against crime.
    — Megan Janetsky, Los Angeles Times, 30 Oct. 2026
  • Although 27 years have passed since Bessette Kennedy, her husband and her sister Lauren Bessette perished in a fatal private plane crash off the coast of Martha’s Vineyard, the former Calvin Klein publicist’s influence on fashion carries on.
    — Rosemary Feitelberg, Footwear News, 29 Oct. 2026
Definition of carry on

Browse Nearby Words

actuators
act up
acuity
See all Nearby Words

Cite this Entry

“Act up.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/act%20up. Accessed 2 Nov. 2026.

Copy Citation
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Last Updated: - Updated example sentences

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of satiate

See Definitions and Examples »

Popular in Grammar & Usage

See More

How to Use 'Who' vs. 'Whom'

Merriam-Webster’s Great Big List of Words You Love to Hate

'Affect' vs. 'Effect'

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Why is '-ed' sometimes pronounced at the end of a word?
See More

Popular in Wordplay

See More

The Longest Long Words List

9 Words That Sound Like Insults But Aren't

Pwn, Skibidi, Girlboss and Other Words Added to the 2026 Scrabble Dictionary

Ten More Words from Taylor Swift Songs

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

How to Use 'Who' vs. 'Whom'

The Longest Long Words List

9 Words That Sound Like Insults But Aren't
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
couple-laugh-cafe
Quiz: Foreign Phrases You Should Know Check out your bona fides and avoid any faux pas.
See All