Etymology: Middle English, partly from Latin actus doing, act, from agere to drive, do; partly from Latin actum thing done, record, from neuter of actus, past participle of agere — more at agent
Date: 14th century
a. the doing of a thing ; deed
b. something done voluntarily
2. a state of real existence rather than possibility
3. the formal product of a legislative body ; statute; also a decision or determination of a sovereign, a legislative council, or a court of justice
4. the process of doing ; action <caught in the act> 5. often capitalized a formal record of something done or transacted 6. one of the principal divisions of a theatrical work (as a play or opera) 7. a. one of successive parts or performances (as in a variety show or circus) b. the performer or performers in such an act c. a performance or presentation identified with a particular individual or group d. the sum of a person's actions or effects that serve to create an impression or set an example <a hard act to follow> 8. a display of affected behavior ; pretense II. Date: 1590 transitive verb 1. obsolete actuate, animate 2. a. to represent or perform by action especially on the stage b. feign, simulate c. impersonate 3. to play the part of as if in a play <act the man of the world> 4. to behave in a manner suitable to <act your age> intransitive verb 1. a. to perform on the stage b. to behave as if performing on the stage ; pretend 2. to take action ; move <think before acting> <acted favorably on the recommendation> 3. to conduct oneself ; behave <act like a fool> 4. to perform a specified function ; serve <trees acting as a windbreak> 5. to produce an effect ; work <wait for a medicine to act> 6. of a play to be capable of being performed <the play acts well> 7. to give a decision or award <adjourned without acting on the bill> • actability noun • actable adjective III. abbreviation 1. active 2. actor 3. actual
New Collegiate Dictionary. 2001.