ACT, v.i. [Gr., Lat. to urge, drive, lead, bring, do, perform, or in general to move, to exert force.]

1. The exertion of power; the effect, of which power exerted is the cause; as, the act of giving or receiving. In this sense, it denotes an operation of the mind. Thus, to discern is an act of the understanding; to judge is an act of the will.
2. That which is done; a deed, exploit, or achievement, whether good or ill. And his miracles and his acts which he did in the midst of Egypt. – Deut. xi.
3. Action; performance; production of effects; as, an act of charity. But this sense is closely allied to the foregoing.
4. A state of reality or real existence, as opposed to a possibility. The seeds of plants are not at first in act, but in possibility, what they afterwards grow to be. – Hooker.
5. In general, act denotes action completed; but preceded by in, it denotes incomplete action. She was taken in the very act. – John viii. In act is used also to signify incipient action, or a state of preparation to exert power; as, "In act to strike," a poetical use.
6. A part or division of a play to be performed without interruption; after which the action is suspended to give respite to the performers. Acts are divided into smaller portions, called scenes.
7. The result of public deliberation, or the decision of a prince, legislative body, council, court of justice, or magistrate; a decree, edict, law, judgment, resolve, award, determination; as, an act of parliament, or of congress. The term is also transferred to the book, record, or writing, containing the laws and determinations. Also, any instrument in writing to verify facts. In the sense of agency, or power to produce effects, as in the passage cited by Johnson from Shakspeare, the use is improper. To try the vigor of them, and apply Allayments to their act. Act, in English Universities, is a thesis maintained in public, by a candidate for a degree, or to show the proficiency of a student. At Oxford, the time when masters and doctors complete their degrees is also called the act, which is held with great solemnity. At Cambridge, as in the United States, it is called commencement. – Encyc. Act of faith, auto da fé, in Catholic countries, is a solemn day held by the Inquisition, for the punishment of heretics, and the absolution of accused persons found innocent; or it is the sentence of the Inquisition. Acts of the Apostles, the title of a book in the New Testament, containing a history of the transactions of the Apostles. Acta Diurna, among the Romans, a sort of Gazette, containing an authorized account of transactions in Rome, nearly similar to our newspapers. Acta Populi, or Acta Publica, the Roman registers of assemblies, trials, executions, buildings, births, marriages, and deaths of illustrious persons, &c. Acta Senatus, minutes of what passed in the Roman senate, called also Commentarii, commentaries.

1. To exert power; as, the stomach acts upon food; the will acts upon the body in producing motion.
2. To be in action or motion; to move. He hangs between in doubt to act or rest. – Pope.
3. To behave, demean, or conduct, as in morals, private duties, or public offices; as, we know not why a minister has acted in this manner. But in this sense, it is most frequent in popular language; as, how the man acts or has acted. To act up to, is to equal in action; to fulfill, or perform a correspondent action; as, he has acted up to his engagement or his advantages.

1. To perform; to represent a character on the stage. Act well your part, there all the honor lies. – Pope.
2. To feign or counterfeit. [Obs. or improper.] With acted fear the villain thus pursued. – Dryden.
3. To put in motion; to actuate; to regulate movements. Most people in the world are acted by levity. – South. Locke. [In this latter sense obsolete, and superseded by Actuate, which see.]

1. That which is done or doing; the exercise of power, or the effect, of which power exerted is the cause; a performance; a deed.
   
   

   That best portion of a good man's life,
   His little, nameless, unremembered acts
   Of kindness and of love.
   Wordsworth.

   Hence, in specific uses: (a)

2. To move to action; to actuate; to animate.
   
   
   [Obs.]

   Self-love, the spring of motion, acts the soul.
   Pope.

3. To exert power; to produce an effect; as, the stomach acts upon food.
4. A state of reality or real existence as opposed to a possibility or possible existence.
   
   
   [Obs.]

   The seeds of plants are not at first in act, but in possibility, what they afterward grow to be.
   Hooker.

5. To perform; to execute; to do.
   
   
   [Archaic]

   That we act our temporal affairs with a desire no greater than our necessity.
   Jer. Taylor.

   Industry doth beget by producing good habits, and facility of acting things expedient for us to do.
   Barrow.

   Uplifted hands that at convenient times
   Could act extortion and the worst of crimes.
   Cowper.

6. 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.
   
   

   He hangs between, in doubt to act or rest.
   Pope.

7. Process of doing; action. In act, in the very doing; on the point of (doing).
   
   
   "In act to shoot." Dryden.

   This woman was taken . . . in the very act.
   John viii. 4.

   Act of attainder. (Law) See Attainder. -- Act of bankruptcy (Law), an act of a debtor which renders him liable to be adjudged a bankrupt. -- Act of faith. (Ch. Hist.) See Auto-da-Fé. -- Act of God (Law), an inevitable accident; such extraordinary interruption of the usual course of events as is not to be looked for in advance, and against which ordinary prudence could not guard. -- Act of grace, an expression often used to designate an act declaring pardon or amnesty to numerous offenders, as at the beginning of a new reign. -- Act of indemnity, a statute passed for the protection of those who have committed some illegal act subjecting them to penalties. Abbott. -- Act in pais, a thing done out of court (anciently, in the country), and not a matter of record.

   Syn. -- See Action.

8. To perform, as an actor; to represent dramatically on the stage.
9. To behave or conduct, as in morals, private duties, or public offices; to bear or deport one's self; as, we know not why he has acted so.
10. To assume the office or character of; to play; to personate; as, to act the hero.
11. To perform on the stage; to represent a character.
    
    

    To show the world how Garrick did not act.
    Cowper.

    To act as or for, to do the work of; to serve as. -- To act on, to regulate one's conduct according to. -- To act up to, to equal in action; to fulfill in practice; as, he has acted up to his engagement or his advantages.

12. To feign or counterfeit; to simulate.
    
    

    With acted fear the villain thus pursued.
    Dryden.

    To act a part, to sustain the part of one of the characters in a play; hence, to simulate; to dissemble. -- To act the part of, to take the character of; to fulfill the duties of.