\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

This week is shaping as a big one for synth-pop act Years & Years, whose top sophomore album Palo Santo is aiming for a high debut on the U.K. chart. Billboard Staff, Billboard, "Watch Years & Years Cover Ariana Grande's 'No Tears Left To Cry' For BBC Radio 1," 13 July 2018 The tour features rock acts Chuck Negron, The Association, Gary Puckett & the Union Gap, Mark Lindsay, The Cowsills, and, of course, The Turtles, whose hit song Happy Together gave the tour its name. Adesuwa Agbonile, sacbee, "5 Cal State Fair musical acts you don’t want to miss this year," 13 July 2018 This year’s lineup is a genre-bending hodgepodge of both popular and emerging acts. Lisa Deaderick,, "Top weekend events: San Diego Pride, Sun & Sea Festival, Gustavo Romero," 13 July 2018 This is about learning the secrets behind the magician's most incredible act and the ensuing legacy that lives on in Cincinnati, Bengals and NFL history. Jim Owczarski,, "The No. 2 Cincinnati Bengals play in last 30 years: Jerome Simpson’s flip," 12 July 2018 Boosting military budgets is aimed at making NATO a more capable and battle-ready force to help prevent aggressive acts by Russia and other rivals. Robert Wall, WSJ, "Trump Unsettles NATO Allies With Demands as He Backs Alliance," 12 July 2018 Stated differently, by criticizing an entire program, the NCAA allegedly imputed wrongful acts on members of the program who were innocent. Michael Mccann,, "Should the NCAA Be Worried About the Lawsuit It's Facing From Former Louisville Players?," 12 July 2018 The descriptive text is quite graphic, mentioning fetish acts and featuring rambling stories that paint women as promiscuous. Chris Morris, Fortune, "Walmart Was Once Again Forced to Pull an Offensive Shirt From Its Website," 12 July 2018 More than 100 musical acts are scheduled during Labor Day weekend in Milwaukee. Harley Davidson Motor Company, Milwaukee Journal Sentinel, "How to access more at Harley’s 115th party," 12 July 2018

Recent Examples on the Web: Verb

Utilizing some slick visual effects, Grande sways her body back and forth, with the galaxy acting like a hula hoop swaying around her. Connor Whittum, Billboard, "Ariana Grande's Epic 'God Is a Woman' Video, Decoded," 13 July 2018 In 2001, Highmore had another chance to act opposite a family member. Temi Adebowale, Country Living, "How Freddie Highmore Went From Child Actor to Star of 'The Good Doctor'," 11 July 2018 Then, challenge your conversation partner with a call to act. Charli Cooksey, Teen Vogue, "How to Have Uncomfortable Conversations," 10 July 2018 His deputy, Andrew Wheeler, is taking over as acting director. Maya Miller, Scientific American, "Embattled EPA Chief Scott Pruitt Resigns--What's Next?," 5 July 2018 By Jeff Siner Republican council member Ed Driggs was also a key player, acting as a liaison between the city and Republican U.S. Sen. Thom Tillis and other Republicans. Steve Harrison And Jim Morrill, charlotteobserver, "Why did council Democrats wait to oppose RNC? An inside look at Charlotte’s bid.," 13 July 2018 Bolutife Olorunda, 29, of Vancouver, pleaded guilty on Tuesday to federal assault after he was accused of acting erratically on a May 30 flight from Portland, Oregon, to Atlanta, the Associated Press reports. Char Adams,, "Washington Man Forced to Pay Delta Airlines and Faces Jail After Causing Emergency Landing," 12 July 2018 Morgan, acting on behalf of ALS patient Cathy Jordan, sued the state last year after the Legislature passed laws banning the sale of smoking products, citing a health risk. Steven Lemongello,, "Medical marijuana protesters call for Gov. Rick Scott to allow smokable pot," 11 July 2018 Meanwhile, an interior green wall is designed to purify air and an exterior plant wall acts as a foundation for micro-farming. Liz Stinson, Curbed, "Tiny house from UN Environment and Yale raises the bar for eco-living," 11 July 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

15 Oct 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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