from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The process of doing or performing something: the act of thinking.
  • n. Something done or performed; a deed: a charitable act.
  • n. A product, such as a statute, decree, or enactment, resulting from a decision by a legislative or judicial body: an act of Congress.
  • n. A formal written record of proceedings or transactions.
  • n. One of the major divisions of a play or opera.
  • n. A performance or entertainment usually forming part of a longer presentation: a juggling act; a magic act.
  • n. The actor or actors presenting such a performance: joined the act in Phoenix.
  • n. A manifestation of intentional or unintentional insincerity; a pose: put on an act.
  • transitive v. To play the part of; assume the dramatic role of: She plans to act Lady Macbeth in summer stock.
  • transitive v. To perform (a role) on the stage: act the part of the villain.
  • transitive v. To behave like or pose as; impersonate: Don't act the fool.
  • transitive v. To behave in a manner suitable for: Act your age.
  • intransitive v. To behave or comport oneself: She acts like a born leader.
  • intransitive v. To perform in a dramatic role or roles.
  • intransitive v. To be suitable for theatrical performance: This scene acts well.
  • intransitive v. To behave affectedly or unnaturally; pretend.
  • intransitive v. To appear or seem to be: The dog acted ferocious.
  • intransitive v. To carry out an action: We acted immediately. The governor has not yet acted on the bill.
  • intransitive v. To operate or function in a specific way: His mind acts quickly.
  • intransitive v. To serve or function as a substitute for another: A coin can act as a screwdriver.
  • intransitive v. To produce an effect: waited five minutes for the anesthetic to act.
  • act out To perform in or as if in a play; represent dramatically: act out a story.
  • act out To realize in action: wanted to act out his theory.
  • act out To express (unconscious impulses, for example) in an overt manner without conscious understanding or regard for social appropriateness.
  • act up To misbehave.
  • act up To malfunction.
  • act up Informal To become active or troublesome after a period of quiescence: My left knee acts up in damp weather. Her arthritis is acting up again.
  • idiom be in on the act To be included in an activity.
  • idiom clean up (one's) act Slang To improve one's behavior or performance.
  • idiom get into the act To insert oneself into an ongoing activity, project, or situation.
  • idiom get (one's) act together Slang To get organized.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. Something done, a deed.
  • n. Actuality.
  • n. A product of a legislative body, a statute.
  • n. The process of doing something.
  • n. A formal or official record of something done.
  • n. A division of a theatrical performance.
  • n. A performer or performers in a show.
  • n. Any organized activity.
  • n. A display of behaviour.
  • v. To do something.
  • v. To perform a theatrical role.
  • v. To behave in a certain way.
  • v. To convey an appearance of being.
  • v. To have an effect (on).
  • v. To play (a role).
  • v. To feign.
  • v. To map via a homomorphism to a group of automorphisms (of).

from the GNU version of the Collaborative International Dictionary of English

  • n. That which is done or doing; the exercise of power, or the effect, of which power exerted is the cause; a performance; a deed.
  • n. The result of public deliberation; the decision or determination of a legislative body, council, court of justice, etc.; a decree, edit, law, judgment, resolve, award.
  • n. A formal solemn writing, expressing that something has been done.
  • n. A performance of part of a play; one of the principal divisions of a play or dramatic work in which a certain definite part of the action is completed.
  • n. A thesis maintained in public, in some English universities, by a candidate for a degree, or to show the proficiency of a student.
  • n. A state of reality or real existence as opposed to a possibility or possible existence.
  • n. Process of doing; action. In act, in the very doing; on the point of (doing).
  • intransitive v. To exert power; to produce an effect.
  • intransitive v. To perform actions; to fulfill functions; to put forth energy; to move, as opposed to remaining at rest; to carry into effect a determination of the will.
  • intransitive v. To behave or conduct, as in morals, private duties, or public offices; to bear or deport one's self.
  • intransitive v. To perform on the stage; to represent a character.
  • transitive v. To move to action; to actuate; to animate.
  • transitive v. To perform; to execute; to do.
  • transitive v. To perform, as an actor; to represent dramatically on the stage.
  • transitive v. To assume the office or character of; to play; to personate.
  • transitive v. To feign or counterfeit; to simulate.

from The Century Dictionary and Cyclopedia

  • To do, perform, or transact.
  • To represent by action; perform on or as on the stage; play, or play the part of; hence, feign or counterfeit: as, to act Macbeth; to act the lover, or the part of a lover.
  • To perform the office of; assume the character of: as, to act the hero.
  • To put in action; actuate.
  • To do something; exert energy or force in any way: used of anything capable of movement, either original or communicated, or of producing effects. Specifically
  • To put forth effort or energy; exercise movement or agency; be employed or operative: as, to act vigorously or languidly; he is acting against his own interest; his mind acts sluggishly.
  • To exert influence or produce effects: perform a function or functions; operate: as, praise acts as a stimulant; mind acts upon mind; the medicine failed to act; the brake refused to act, or to act upon the wheels.
  • To be employed or operate in a particular way; perform specific duties or functions: as, a deputy acts for or in place of his principal; he refused to act on or as a member of the committee.
  • To perform as an actor; represent a character; hence, to feign or assume a part: as, he acts well; he is only acting.
  • He is a man of sentiment, and acts up to the sentiments he professes. Sheridan, School for Scandal, i. 2. Synonyms Act, Work, Operate. These words agree in expressing the successful exertion of power. In their intransitive use they are sometimes interchangeable: as, a medicine acts, works, or operates; a plan works or operates. Where they differ, act may more often refer to a single action or to the simpler forms of action: as, a machine works well when all its parts act. Act may also be the most general, applying to persons or things, the others applying generally to things. Operate, may express the more elaborate forms of action. Work may express the more powerful kinds of action: as, it worked upon his mind.
  • n. An exertion of energy or force, physical or mental; anything that is done or performed; a doing or deed; an operation or performance.
  • n. A state of real existence, as opposed to a possibility, power, or being in germ merely; actuality; actualization; entelechy.
  • n. The soul, according to the Aristotelians, is the act, that is, is the entelechy or perfect development of the body. So God is said to be pure act, for Aristotle says, “There must be a principle whose essence it is to be actual (η%148ς ἠ ον)σία ἐνε)ργεια),” and this is by many writers understood to mean “whose essence is to be active.” In the phrase in act, therefore, act, though properly meaning actuality, is often used to mean activity.
  • n. A part or division of a play performed consecutively or without a fall of the curtain, in which a definite and coherent portion of the plot is represented: generally subdivided into smaller portions, called scenes.
  • n. The result of public deliberation, or the decision of a prince, legislative body, council, court of justice, or magistrate; a decree, edict, law, statute, judgment, resolve, or award: as, an act of Parliament or of Congress; also, in plural, proceedings; the formal record of legislative resolves or of the doings of individuals.
  • n. In universities, a public disputation or lecture required of a candidate for a degree of master.
  • n. [Such a synopsis (cedula), stating the time of studies, the acts made, and the degrees taken by the candidate, and duly sworn to, had usually been required in universities since the middle ages.]
  • n. In law, an instrument or deed in writing, serving to prove the truth of some bargain or transaction: as, I deliver this as my act and deed.
  • n. In theology, something done at once and once for all, as distinguished from a work.
  • n. A second act (1890) which provided for an annual appropriation, to be increased in ten years from $15,000 to a permanent sum of $25,000 from the proceeds of the sale of public land, for the more complete endowment of these institutions. This income could be applied only to instruction (with facilities) in agriculture, the mechanic arts, the English language, and other branches directly related to industrial life.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • v. perform on a stage or theater
  • v. have an effect or outcome; often the one desired or expected
  • v. be engaged in an activity, often for no particular purpose other than pleasure
  • n. a short theatrical performance that is part of a longer program
  • n. something that people do or cause to happen
  • n. a subdivision of a play or opera or ballet
  • v. pretend to have certain qualities or state of mind
  • v. be suitable for theatrical performance
  • v. behave in a certain manner; show a certain behavior; conduct or comport oneself
  • n. a manifestation of insincerity
  • v. play a role or part
  • n. a legal document codifying the result of deliberations of a committee or society or legislative body
  • v. behave unnaturally or affectedly
  • v. perform an action, or work out or perform (an action)
  • v. discharge one's duties


from The American Heritage® Dictionary of the English Language, 4th Edition

Middle English, from Old French acte, from Latin āctus, a doing, and āctum, a thing done, both from past participle of agere, to drive, do.

from Wiktionary, Creative Commons Attribution/Share-Alike License

Old French acte, from Latin ācta ("register of events"), plural of āctum ("decree, law"), from agō ("put in motion").


  • 'Abortion is a racist, genocidal act' yahooBuzzArticleHeadline = '\'Abortion is a racist, genocidal act\' '; yahooBuzzArticleSummary =' Article: Info on the latest anti-abortion propaganda. '

    'Abortion is a racist, genocidal act'

  • As I consider it one of the most important qualifications in a judge to have the discernment I refer to, and as many are appointed judges, even at our national shows, _who never should have been appointed, and many act who never should act_, it ought to be put out of all doubt.

    Cattle and Cattle-breeders

  • So far as the Scriptures seem to suggest there is not a fresh act upon God's part at certain times in one's experience, but His wondrous love is such that there is _a continuous act_ -- a continuous flooding in of all the gracious power of His Spirit that the human conditions will admit of.

    Quiet Talks on Power

  • Or do we find, when we are engaged in an act of the will, that the mental stream contains only the familiar old elements of attention, perception, judgment, desire, purpose, etc., _all organized or set for the purpose of accomplishing or preventing some act_?

    The Mind and Its Education

  • Absolute -- all this begetting of Divine Children -- was in the nature of a single act rather than as a series of acts, if we may be permitted to speak of the manifestation as an _act_.

    A Series of Lessons in Raja Yoga

  • Yes, if you consider the amusement in the abstract: but if you take it as _this human act_, the act is inordinate and evil in itself, or as it is elicited in the mind of the agent.

    Moral Philosophy

  • My father is very anxious, I think, to act the play; my mother, to have it published before it is acted; and I sit and hear it discussed and praised and criticised, only longing (like a "silly wench," as my mother calls me when I confess as much to her) to see my father in his lovely dress and hear the _alarums of my fifth act_.

    Records of a Girlhood

  • Miss Brown, I'll give in, that you and Mr. Brown _do_ act up to your principles; you certainly _act_ as if you were willing to be damned '; -- and so do all those folks who will live on the blood and groans of the poor Africans, as the Doctor said; and I should think, by the way Newport people are making their money, that they were all pretty willing to go that way, -- though, whether it's for the glory of God, or not, I'm doubting.

    The Atlantic Monthly, Volume 04, No. 21, July, 1859

  • _acting_, His _essence_ being _to act_, for otherwise he might _never_ have acted, and the existence of the world would be an accident; for what should have, in that case, decided Him to act, after long inactivity?

    Morals and Dogma of the Ancient and Accepted Scottish Rite of Freemasonry

  • Wherefore if the mind should prefer a weak inclination to a strong one, _it would act against itself, and otherwise than it is disposed to act_.”

    A Theodicy, or, Vindication of the Divine Glory


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