act

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The process of doing or performing something: the act of thinking.
2. n. Something done or performed; a deed: a charitable act.
3. n. A product, such as a statute, decree, or enactment, resulting from a decision by a legislative or judicial body: an act of Congress.
4. n. A formal written record of proceedings or transactions.
5. n. One of the major divisions of a play or opera.
6. n. A performance or entertainment usually forming part of a longer presentation: a juggling act; a magic act.
7. n. The actor or actors presenting such a performance: joined the act in Phoenix.
8. n. A manifestation of intentional or unintentional insincerity; a pose: put on an act.
9. v. To play the part of; assume the dramatic role of: She plans to act Lady Macbeth in summer stock.
10. v. To perform (a role) on the stage: act the part of the villain.
11. v. To behave like or pose as; impersonate: Don't act the fool.
12. v. To behave in a manner suitable for: Act your age.
13. v. To behave or comport oneself: She acts like a born leader.
14. v. To perform in a dramatic role or roles.
15. v. To be suitable for theatrical performance: This scene acts well.
16. v. To behave affectedly or unnaturally; pretend.
17. v. To appear or seem to be: The dog acted ferocious.
18. v. To carry out an action: We acted immediately. The governor has not yet acted on the bill.
19. v. To operate or function in a specific way: His mind acts quickly.
20. v. To serve or function as a substitute for another: A coin can act as a screwdriver.
21. v. To produce an effect: waited five minutes for the anesthetic to act.
22. act out To perform in or as if in a play; represent dramatically: act out a story.
23. act out To realize in action: wanted to act out his theory.
24. act out To express (unconscious impulses, for example) in an overt manner without conscious understanding or regard for social appropriateness.
25. act up To misbehave.
26. act up To malfunction.
27. 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.
28. idiom. be in on the act To be included in an activity.
29. idiom. clean up (one's) act Slang To improve one's behavior or performance.
30. idiom. get into the act To insert oneself into an ongoing activity, project, or situation.
31. idiom. get (one's) act together Slang To get organized.

Century Dictionary and Cyclopedia

1. n. An exertion of energy or force, physical or mental; anything that is done or performed; a doing or deed; an operation or performance.
2. n. A state of real existence, as opposed to a possibility, power, or being in germ merely; actuality; actualization; entelechy.
3. 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.
4. 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.
5. 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. Acts are of two kinds: general or public, which are of general application; and private, which relate to particular persons or concerns. A law or statute proposed in a legislative body, then called a bill, becomes an act after having been passed by both branches and signed by the chief executive officer; but in a few of the United States the governor's signature is not necessary. British acts are usually referred to by mentioning them simply by the regnal year and number of chapter: as, act of 7 and 8 Vict. c. 32. American acts, particularly acts of Congress, are often referred to simply by date: as, act of May 6, 1882.
6. n. In universities, a public disputation or lecture required of a candidate for a degree of master. The performer is said to “keep the act.” Hence, at Cambridge, the thesis and examination for the degree of doctor; at Oxford, the occasion of the completion of degrees. So, act holiday, act feast. The candidate who keeps the act is also himself called the act. In medieval, and sometimes in modern scholastic use, any public defense of a thesis by way of disputation is called an act.
7. 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.]
8. 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. The term is used to show the connection between the instrument and the party who has given it validity by his signature or by his legal assent; when thus perfected, the instrument becomes the act of the parties who have signed it or assented to it in a form required by law. Edw. Livingston.
9. n. In theology, something done at once and once for all, as distinguished from a work. Thus, justification is said to be an act of God's free grace, but sanctification is a work carried on through life.
10. To do, perform, or transact.
11. 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.
12. To perform the office of; assume the character of: as, to act the hero.
13. To put in action; actuate.
14. 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
15. 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.
16. 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.
17. 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. Often used with reference to the performance of duties by a temporary substitute for the regular incumbent of an office: as, the lieutenant-governor will act in the absence of the governor. See acting.
18. To perform as an actor; represent a character; hence, to feign or assume a part: as, he acts well; he is only acting.
19. 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.
20. 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.

Wiktionary

1. n. countable Something done, a deed.
2. n. obsolete, uncountable Actuality.
3. n. countable A product of a legislative body, a statute.
4. n. The process of doing something.
5. n. countable A formal or official record of something done.
6. n. countable A division of a theatrical performance.
7. n. countable A performer or performers in a show.
8. n. countable Any organized activity.
9. n. countable A display of behaviour.
10. v. intransitive To do something.
11. v. intransitive To perform a theatrical role.
12. v. intransitive To behave in a certain way.
13. v. copulative To convey an appearance of being.
14. v. intransitive To have an effect (on).
15. v. transitive To play (a role).
16. v. transitive To feign.
17. v. mathematics, intransitive, of a group To map via a homomorphism to a group of automorphisms (of).

GNU Webster's 1913

1. 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.
2. 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.
3. n. A formal solemn writing, expressing that something has been done.
4. 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.
5. n. A thesis maintained in public, in some English universities, by a candidate for a degree, or to show the proficiency of a student.
6. n. obsolete A state of reality or real existence as opposed to a possibility or possible existence.
7. n. Process of doing; action. In act, in the very doing; on the point of (doing).
8. v. obsolete To move to action; to actuate; to animate.
9. v. Archaic To perform; to execute; to do.
10. v. To perform, as an actor; to represent dramatically on the stage.
11. v. To assume the office or character of; to play; to personate.
12. v. To feign or counterfeit; to simulate.
13. v. To exert power; to produce an effect.
14. 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.
15. v. To behave or conduct, as in morals, private duties, or public offices; to bear or deport one's self.
16. v. To perform on the stage; to represent a character.

WordNet 3.0

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