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noun \ˈakt\

Simple Definition of act

  • : something that is done

  • : a law made by a group of legislators

  • : one of the main divisions of a play or opera

Source: Merriam-Webster's Learner's Dictionary

Full Definition of act

  1. 1 a :  the doing of a thing :  deed b :  something done voluntarily

  2. 2 :  a state of real existence rather than possibility

  3. 3 :  the formal product of a legislative body :  statute; also :  a decision or determination of a sovereign, a legislative council, or a court of justice

  4. 4 :  the process of doing :  action <caught in the act>

  5. 5 often capitalized :  a formal record of something done or transacted

  6. 6 :  one of the principal divisions of a theatrical work (as a play or opera)

  7. 7 a :  one of successive parts or performances (as in a variety show or circus) b :  the performer or performers in such an act c :  a performance or presentation identified with a particular individual or group 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>

  8. 8 :  a display of affected behavior :  pretense

into the act or in on the act
  1. :  into an undertaking or situation as an active participant

Examples of act in a sentence

  1. We were grateful for her many acts of kindness.

  2. the Civil Rights Act of 1964

  3. Please read act II, scene 1 of Shakespeare's Romeo and Juliet.

  4. In the first act, two characters are talking in a restaurant.

Origin of act

Middle English, partly from Latin actus doing, act, from agere to drive, do; partly from Latin actum thing done, record, from neuter of actus, past participle of agere — more at agent

First Known Use: 14th century




Simple Definition of act

  • : to do something : to take action

  • : to behave in a particular way

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

Source: Merriam-Webster's Learner's Dictionary

Full Definition of act

  1. transitive verb
  2. 1 obsolete :  actuate, animate

  3. 2 a :  to represent or perform by action especially on the stage b :  feign, simulate c :  impersonate

  4. 3 :  to play the part of as if in a play <act the man of the world>

  5. 4 :  to behave in a manner suitable to <act your age>

  6. intransitive verb
  7. 1 a :  to perform on the stage b :  to behave as if performing on the stage :  pretend

  8. 2 :  to take action :  move <think before acting> <acted favorably on the recommendation>

  9. 3 :  to conduct oneself :  behave <act like a fool>

  10. 4 :  to perform a specified function :  serve <trees acting as a windbreak>

  11. 5 :  to produce an effect :  work <wait for a medicine to act>

  12. 6 of a play :  to be capable of being performed <the play acts well>

  13. 7 :  to give a decision or award <adjourned without acting on the bill>

actabilityplay \ˌak-tə-ˈbi-lə-tē\ noun
actable play \ˈak-tə-bəl\ adjective

Examples of act in a sentence

  1. He knew he had to act quickly.

  2. The government was slow to act.

  3. She acted on behalf of her father, who was not at the meeting.

  4. I believe that the killer acted alone.

  5. She had acted in self-defense when she killed her attacker.

  6. We were acting in the best interests of our children.

  7. We must act soon to end this crisis.

  8. She learned at an early age how to act properly in social situations.

  9. People are always telling me how I should act and what I should say.

  10. I noticed that the dog was acting funny this morning.


First Known Use of act





Definition of act

  1. 1 active

  2. 2 actor

  3. 3 actual

Other Performing Arts Terms




Definition of ACT

  1. 1 Action for Children's Television

  2. 2 Association of Classroom Teachers

  3. 3 Australian Capital Territory



trademark \ˌā-ˌsē-ˈtē\

Definition of ACT

  1. —used for a standardized achievement test to evaluate suitability for college admission

ACT Defined for Kids



noun \ˈakt\

Definition of act for Students

  1. 1 :  something that is done :  deed <an act of bravery>

  2. 2 :  a law made by a governing body

  3. 3 :  a main division of a play

  4. 4 :  one of the performances in a show <a juggling act>

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




Definition of act for Students


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

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

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

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

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

act up
  1. :  to behave badly

Law Dictionary




Legal Definition of act

  1. 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

  2. 2a often cap :  the formal product of a legislative body :  the formally declared will of a legislature the final requirement of which is usu. the signature of the proper executive officer :  statute <an ACct of Congress> <in furtherance of the purposes…of that ACctU.S. Code> b :  a decision or determination of a sovereign, a legislative council, or a court of justice — compare bill 1

  3. 3 often cap :  a formal record of something done or transacted <given as my free ACct and deed>



intransitive verb

Legal Definition of act

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

  2. 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 President — U.S. Constitution art. II>

  3. 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>

actor \ˈak-tər\ play noun

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