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; as, an act of Parliament, or of Congress.

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.) 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. t.) To move to action; to actuate; to animate.

9. (v. t.) To perform; to execute; to do.

10. (v. t.) To perform, as an actor; to represent dramatically on the stage.

11. (v. t.) To assume the office or character of; to play; to personate; as, to act the hero.

12. (v. t.) To feign or counterfeit; to simulate.

13. (v. i.) To exert power; to produce an effect; as, the stomach acts upon food.

14. (v. i.) 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. i.) 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.

16. (v. i.) To perform on the stage; to represent a character.