ACT

UK:**UK and possibly other pronunciationsUK and possibly other pronunciations/ˈækt/US:USA pronunciation: IPA and respellingUSA pronunciation: IPA/ækt/ ,USA pronunciation: respelling(akt)


Collins Concise English Dictionary © HarperCollins Publishers::
ACT abbreviation for
  1. Australian Capital Territory
  2. (formerly in Britain) advance corporation tax
ACT /ækt/ n acronym for
  1. (in New Zealand) Association of Consumers and Taxpayers: a small political party of the right
WordReference Random House Learner's Dictionary of American English © 2026
-act-, root. 
    1. -act- comes from Latin, where it has the meaning "to do, move''. It is related to the root -ag-. This meaning is found in such words as: act, action, exact, inexact, transact.

act /ækt/USA pronunciation   n. [countable]
  1. anything done or to be done;
    deed:an act of mercy.
  2. the process of doing: caught in the act.
  3. Government[sometimes: Act] a formal decision, law, or the like;
    a decree or edict:an act of Congress.
  4. Show Businessone of the main divisions of a play or opera: a drama in three acts.
    • Show Businessa short performance by one or more entertainers, usually part of a variety show, circus, etc.:an acrobatic act.
  6. a display of insincere behavior assumed for effect;
    pretense:[usually singular]Her apology was all an act.

v. 
  1. [no object] to do something;
    carry out an action.
  2. to reach or issue a decision on some matter:[no object;(~ + on + object)]Congress failed to act (on the tax bill).
  3. [no obj] to operate or function in a particular way:acted as manager.
  4. to produce an effect: The medicine failed to act.
  5. to conduct oneself in a particular fashion: [no object]acted foolishly.[~ + object]to act one's age.
  6. [no obj] to pretend;
    feign:was just acting and wasn't really sorry.
  7. Show Businessto perform as an actor: [no object]has acted on Broadway.[~ + object]to act Macbeth.
  8. act on or upon, [~ + on/upon + object]
    • to act in accordance with;
      follow:will act on (upon) your wishes immediately.
    • to have an effect on;
      affect:The aspirin acted on the pain.
  9. act out,
    • [ ~ + out + obj] to show or express by gestures or actions:He acted out his frustrations by throwing things.
    • to perform: [ ~ + out + obj]:The students acted out the roles in the play.[ ~ + obj + out]:to act the roles out.
  10. act up, [no object]
    • to fail to function properly:The car's transmission is acting up.
    • to behave willfully:The tired, cranky child acted up during the wedding.
    • (of a recurring ailment) to become troublesome:His rheumatism is acting up.
Idioms
  1. Idioms clean up one's act, to begin to behave in a more socially acceptable way.
  2. Idioms get or have one's act together, to behave or function responsibly and efficiently.

  • Idioms in the act of, in the process of:was caught in the act of climbing out the window.
    • See -act-.
    WordReference Random House Unabridged Dictionary of American English © 2026
    act  (akt),USA pronunciation n. 
    1. anything done, being done, or to be done;
      deed;
      performance:a heroic act.
    2. the process of doing:caught in the act.
    3. Governmenta formal decision, law, or the like, by a legislature, ruler, court, or other authority;
      decree or edict;
      statute;
      judgment, resolve, or award:an act of Congress.
    4. an instrument or document stating something done or transacted.
    5. Show Businessone of the main divisions of a play or opera:the second act ofHamlet.
    6. Show Businessa short performance by one or more entertainers, usually part of a variety show or radio or television program.
    7. Show Businessthe personnel of such a group:The act broke up after 30 years.
    8. false show;
      pretense;
      feint:The politician's pious remarks were all an act.
    9. Philosophy(in scholasticism)
      • activity in process;
        operation.
      • the principle or power of operation.
      • form as determining essence.
      • a state of realization, as opposed to potentiality.
    10. clean up one's act, [Informal.]to begin adhering to more acceptable practices, rules of behavior, etc.:The factory must clean up its act and treat its employees better.
    11. get or have one's act together, [Informal.]to organize one's time, job, resources, etc., so as to function efficiently:The new administration is still getting its act together.

    v.i. 
    1. to do something;
      exert energy or force;
      be employed or operative:He acted promptly in the emergency.
    2. to reach, make, or issue a decision on some matter:I am required to act before noon tomorrow.
    3. to operate or function in a particular way;
      perform specific duties or functions:to act as manager.
    4. to produce an effect;
      perform a function:The medicine failed to act.
    5. to behave or conduct oneself in a particular fashion:to act well under all conditions.
    6. to pretend;
      feign:Act interested even if you're bored.
    7. Show Businessto perform as an actor:He acted in three plays by Molière.
    8. Show Businessto be capable of being performed:His plays don't act well.
    9. to serve or substitute (usually fol. by for):In my absence the assistant manager will act for me.

    v.t. 
    1. Show Businessto represent (a fictitious or historical character) with one's person:to act Macbeth.
    2. to feign;
      counterfeit:to act outraged virtue.
    3. to behave as:He acted the fool.
    4. [Obs.]to actuate.
    5. act funny, to display eccentric or suspicious behavior.
    6. act on or upon:
      • to act in accordance with;
        follow:He acted on my advice.
      • to have an effect on;
        affect:The stirring music acted on the emotions of the audience.
    7. act one's age, to behave in a manner appropriate to one's maturity:We children enjoyed our uncle because he didn't always act his age.
    8. act out:
      • to demonstrate or illustrate by pantomime or by words and gestures:The party guests acted out stories for one another.
      • Psychologyto give overt expression to (repressed emotions or impulses) without insightful understanding:The patients acted out early traumas by getting angry with the analyst.
    9. act up:
      • to fail to function properly;
        malfunction:The vacuum cleaner is acting up again.
      • to behave willfully:The children always act up in school the day before a holiday.
      • to become painful or troublesome, esp. after a period of improvement or remission:My arthritis is acting up again this morning.
    • Latin āctus a doing (āg- + -tus suffix of verb, verbal action)
    • Latin ācta, plural of āctum something done, noun, nominal use of past participle of agere to do (āg- past participle stem + -tum neuter past participle suffix); and directly
    • Middle French)
    • Middle English act(e) (1350–1400
      1. feat, exploit; achievement; transaction; accomplishment. See action. 4. record. 6. turn, routine. 11. –15. perform, function, work. 17. 18. play.
    ACT, 
      1. American College Test.
      2. EducationAssociation of Classroom Teachers.
      3. Australian Capital Territory.

    act. 
      1. acting.
      2. active.
      3. actor.
      4. actual.

    Collins Concise English Dictionary © HarperCollins Publishers::
    act /ækt/ n
    1. something done or performed; a deed
    2. the performance of some physical or mental process; action
    3. (capital when part of a name) the formally codified result of deliberation by a legislative body; a law, edict, decree, statute, etc
    4. (often plural) a formal written record of transactions, proceedings, etc, as of a society, committee, or legislative body
    5. a major division of a dramatic work
      • a short performance of skill, a comic sketch, dance, etc, esp one that is part of a programme of light entertainment
      • those giving such a performance
    7. an assumed attitude or pose, esp one intended to impress
    8. an occurrence effected by the volition of a human agent, usually opposed at least as regards its explanation to one which is causally determined Compare event
     vb
    1. (intransitive) to do something; carry out an action
    2. (intransitive) to function in a specified way; operate; react: his mind acted quickly
    3. to perform (a part or role) in a play, etc
    4. (transitive) to present (a play, etc) on stage
    5. (intransitive; usually followed by for or as) to be a substitute (for); function in place (of)
    6. (intransitive) followed by as: to serve the function or purpose (of)
    7. (intransitive) to conduct oneself or behave (as if one were): she acts like a teenager
    8. (intransitive) to behave in an unnatural or affected way
    9. (copula) to pose as; play the part of: to act the fool
    10. (copula) to behave in a manner appropriate to (esp in the phrase act one's age)
    11. get in on the act ⇒ informal to become involved in a profitable undertaking or advantageous situation in order to share in the benefits
    12. get one's act together ⇒ informal to become organized or prepared
    Etymology: 14th Century: from Latin actus a doing, performance, and actum a thing done, from the past participle of agere to doˈactable adj ˌactaˈbility n
    'ACT' also found in these entries (note: many are not synonyms or translations):
    abduction - able - ablution - abolition - abridgment - abscission - absolution - abstention - abstinence - abstraction - acceleration - acceptance - access - accession - accessory - acclaim - accommodation - accomplishment - account for - accrual - accumulation - acknowledgment - acquisition - act of God - act on - act up - action - active - actual - actuary - actuate - actus reus - adaptation - addition - adjudicate - adjustment - admittance - adoration - advowson - aestivation - affect - affection - affirmation - agent - agglutination - aggregation - agile - agitate - A, a - abatement

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    Look up "ACT" at Merriam-Webster
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