\ˈakt \

Definition of act 

(Entry 1 of 5)

1a : the doing of a thing : deed an act of courage

b law : something done voluntarily

2 : the process of doing something : action caught in the act

3 : the formal product of a legislative body : statute an act of Congress also : a decision or determination of a sovereign, a legislative council, or a court of justice

4 : one of the principal divisions of a theatrical work (such as a play or opera) a play in three acts

5a : one of successive parts or performances (as in a variety show or circus) a magic act

b : the performer or performers in such an act a two-person comedy act

c : a performance or presentation identified with a particular individual or group They took their act on the road.

d : the sum of a person's actions or effects that serve to create an impression or set an example a hard act to follow

6 : a display of affected behavior : pretense put on an act that deceived nobody His friendly concern was just an act.

7 often capitalized : a formal record of something done or transacted

8 : a state of real existence rather than possibility

into the act or in on the act

: into an undertaking or situation as an active participant saw the success they were having and wanted to get in on the act


acted; acting; acts

Definition of act (Entry 2 of 5)

intransitive verb

1 : to take action : move think before acting acted favorably on the recommendation

2 : to conduct oneself : behave act like a fool

3a : to perform on the stage began acting at the age of eight

b : to behave as if performing on the stage : pretend seemed angry but was just acting

4 : to perform a specified function : serve trees acting as a windbreak

5 : to produce an effect : work wait for a medicine to act

6 : to give a decision or award adjourned without acting on the bill

7 of a play : to be capable of being performed a play that acts well

transitive verb

1a : to represent or perform by action especially on the stage will act the part of Romeo in tonight's play

b : feign, simulate act indifference

c : impersonate

2 : to play the part of as if in a play act the man of the world

3 : to behave in a manner suitable to Act your age.

4 obsolete : actuate, animate


abbreviation (1)

Definition of act (Entry 3 of 5)

1 active

2 actor

3 actual


abbreviation (2)

Definition of ACT (Entry 4 of 5)

1 Action for Children's Television

2 Association of Classroom Teachers

3 Australian Capital Territory



Definition of ACT (Entry 5 of 5)

used for a standardized achievement test to evaluate suitability for college admission

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Other Words from act


actability \ ˌak-​tə-​ˈbi-​lə-​tē \ noun
actable \ ˈak-​tə-​bəl \ adjective

Examples of act in a Sentence


We were grateful for her many acts of kindness. the Civil Rights Act of 1964 Please read act II, scene 1 of Shakespeare's Romeo and Juliet. In the first act, two characters are talking in a restaurant.


He knew he had to act quickly. The government was slow to act. She acted on behalf of her father, who was not at the meeting. I believe that the killer acted alone. She had acted in self-defense when she killed her attacker. We were acting in the best interests of our children. We must act soon to end this crisis. She learned at an early age how to act properly in social situations. People are always telling me how I should act and what I should say. I noticed that the dog was acting funny this morning.
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Recent Examples on the Web: Noun

New walking technologies offer the potential to help those for whom the act is a daily struggle. David Grossman, Popular Mechanics, "Paralyzed Man Walks Again With Surgical Implant," 25 Sep. 2018 And while the acts may be different, the storyline must make sense. Lucia Tonelli, ELLE Decor, "An Exclusive Look Inside Shay Mitchell’s Stunning Office Remodel," 4 Sep. 2018 Oakley was arrested Sunday at the Cosmopolitan casino-resort on the Las Vegas Strip on suspicion of committing or attempting to commit a fraudulent act in a gaming establishment, the Nevada Gaming Control Board said in a statement. NBC News, "Former NBA star Charles Oakley accused of gambling fraud at Las Vegas casino," 12 July 2018 Companies are trying to balance privacy concerns with mounting pressure to do a better job in rooting out workers who might steal, harass or commit violent acts in the workplace. Michael Sasso And Jeff Green,, "Get ready for rolling background checks at work," 11 July 2018 Companies are trying to balance privacy concerns with mounting pressure to do a better job in rooting out workers who might steal, harass or even commit violent acts in the workplace. Bloomberg, Fortune, "Rolling Background Checks at Work Are Becoming a Thing," 11 July 2018 Commission member Max Schachter, the father of 14-year-old Alex Schachter who was among those killed that day, said Cruz committed another act of vandalism previously, but PROMISE was not in place then. Colleen Wright, miamiherald, "Broward's PROMISE program "irrelevant" to Nikolas Cruz's massacre, commission says," 10 July 2018 Her most recent San Diego show was July 1, 2017, as the opening act for The Total Package Tour, which was co-headlined by New Kids On The Block and Boyz II Men. George Varga,, "Paula Abdul to kick off 30th anniversary 'Straight Up Paula!' tour in October," 9 July 2018 Kansas City Mayor Sly James announces Janelle Monae as a headlining act for Kansas City's Open Spaces art festival, which runs from Aug. 25-Oct. Conner Mitchell, kansascity, "KCK's Janelle Monáe coming to Starlight Theatre as part of new citywide arts fest," 9 July 2018

Recent Examples on the Web: Verb

If Denholm acts independently and isn’t seen as deferring to Musk, that may help with both the SEC and DOJ probes. Elizabeth Lopatto, The Verge, "Tesla’s new chairwoman is walking into SEC and DOJ probes," 9 Nov. 2018 And Georgetown Law professor Marty Lederman wrote that Whitaker may qualify for an appointment as acting AG under the Vacancies Reform Act despite not being Senate-confirmed. Andrew Prokop, Vox, "Trump’s dishonest, incoherent defense of naming Matt Whitaker acting attorney general," 9 Nov. 2018 Trump appointed Sessions’s chief of staff at the Department of Justice, Matthew G. Whitaker, as acting attorney general. Vogue, "Attorney General Jeff Sessions Resigns; the Internet Reacts," 7 Nov. 2018 While the device does act as an e-reader or sorts, there's a huge asterisk next to that label. Valentina Palladino, Ars Technica, "Lenovo Yoga Book 2018 review: The keyless keyboard returns, now in E Ink," 2 Nov. 2018 The event calendar is one piece of the company’s new vision for its stores to act as de facto town squares. Andrew Zaleski, Curbed, "Can Apple stores be public spaces?," 3 Oct. 2018 Top with a doughnut, then use a dab of frosting to act as glue and sandwich with another doughnut. Woman's Day Test Kitchen, Woman's Day, "Frankenstein and His Bride Cupcakes," 2 Oct. 2018 Many times parents act as guarantors for their children. Taylor Mead, House Beautiful, "What Every Renter Needs To Know About Getting A Guarantor," 21 Sep. 2018 The tiny mechanical assistants will also act as a redundant communication relay system in order to see whether NASA could rely solely on small satellites for that job in the future. Meghan Bartels,, "Tiny Satellites Headed to Mars Likely Are First of Many," 17 Sep. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'act.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of act


14th century, in the meaning defined at sense 1a


1590, in the meaning defined at intransitive sense 2

History and Etymology for act


Middle English acte, borrowed from Anglo-French & Latin; Anglo-French acte, act, borrowed partly from Latin āctus "driving of cattle, track for cattle, movement, activity, performance, part of a play" (action noun from agere "to drive (cattle), cause to move, do"), partly from Latin āctum (usually in plural) "thing done, public transaction, record," from neuter of āctus, past participle of agere — more at agent


Middle English acten "to act upon, adjudicate," in part derivative of act act entry 1, in part borrowed from Latin āctus, past participle of agere

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Learn More about act

Dictionary Entries near act






act accordingly


Statistics for act

Last Updated

12 Nov 2018

Look-up Popularity

Time Traveler for act

The first known use of act was in the 14th century

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More Definitions for act



English Language Learners Definition of act

 (Entry 1 of 2)

: something that is done

: a law made by a group of legislators

: one of the main divisions of a play or opera



English Language Learners Definition of act (Entry 2 of 2)

: to do something : to take action

: to behave in a particular way

: to behave in a way that is not sincere or honest


\ˈakt \

Kids Definition of act

 (Entry 1 of 2)

1 : something that is done : deed an act of bravery

2 : a law made by a governing body

3 : a main division of a play

4 : one of the performances in a show a juggling act

5 : an insincere way of behaving Her crying was just an act.


acted; acting

Kids Definition of act (Entry 2 of 2)

1 : to do something : move It's important to act quickly in an emergency.

2 : to behave oneself in a certain way He's been acting strangely.

3 : to perform as a character in a play Both stars agreed to act in the movie.

4 : to perform a certain function She'll act as our guide.

5 : to have a result : make something happen : work The medicine acts on the heart.

act up

: to behave badly


\ˈakt \

Medical Definition of act 

(Entry 1 of 3)

1 : a motor performance leading to a definite result

2 : a dealing with objects (as by moving, perceiving, or desiring them)

Medical Definition of act (Entry 2 of 3)

1 : to perform an act : behave

2 : to produce an effect wait for a medicine to act

Medical Definition of act (Entry 3 of 3)


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Legal Definition of act 

(Entry 1 of 2)

1a : something done by a person in accordance with his or her free will a tortious act — see also actus reus

b : the failure to do something that one has a legal duty to do

called also negative act

2a often capitalized : the formal product of a legislative body : the formally declared will of a legislature the final requirement of which is usually the signature of the proper executive officer : statute an act of Congress in furtherance of the purposes…of that actU.S. Code

b : a decision or determination of a sovereign, a legislative council, or a court of justice — compare bill sense 1

3 often capitalized : a formal record of something done or transacted given as my free act and deed

Legal Definition of act (Entry 2 of 2)

1 : to carry into effect a determination of the will : take action

2 : to discharge the duties of a specified office or post : perform a specified function used with a prepositional phrase declaring what officer shall then act as PresidentU.S. Constitution art. II

3 : to give a decision or award (as by vote of a deliberative body or by judicial decree) often used with on adjourned with several important matters still not acted on

Other Words from act

actor \ ˈak-​tər \ noun

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Comments on act

What made you want to look up act? Please tell us where you read or heard it (including the quote, if possible).


obstinately defiant of authority

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