Webster's Revised Unabridged Dictionary · 1913

Act

Act (akt) , noun

[Latin actus, from agere to drive, do: compare French acte. See Agent.]

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
(a)
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; as, an act of Parliament, or of Congress.
(b)
A formal solemn writing, expressing that something has been done.
(c)
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.
(d)
A thesis maintained in public, in some English universities, by a candidate for a degree, or to show the proficiency of a student. — Abbott
2.
A state of reality or real existence as opposed to a possibility or possible existence. [Obsolete]
The seeds of plants are not at first in act, but in possibility, what they afterward grow to be. — Hooker
3.
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
Collocations (7)
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.

Act , transitive verb

[Latin actus, past participle of agere to drive, lead, do; but influenced by English act, n.]

1.
To move to action; to actuate; to animate. [Obsolete]
Self-love, the spring of motion, acts the soul. — Pope
2.
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
3.
To perform, as an actor; to represent dramatically on the stage.
4.
To assume the office or character of; to play; to personate; as, to act the hero.
5.
To feign or counterfeit; to simulate.
With acted fear the villain thus pursued. — Dryden
Collocations (2)
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.

Act , intransitive verb

1.
To exert power; to produce an effect; as, the stomach acts upon food.
2.
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
3.
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.
4.
To perform on the stage; to represent a character.
To show the world how Garrick did not act. — Cowper
Collocations (3)
To act as or To act 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.