act

1. anything done, being done, or to be done; deed; performance:

   a heroic act.

   Synonyms: accomplishment, transaction, achievement, exploit, feat

2. the process of doing:

   caught in the act.

3. a formal decision, law, or the like, by a legislature, ruler, court, or other authority; decree or edict; statute; judgment, resolve, or award:

   an act of Congress.

4. an instrument or document stating something done or transacted.

   Synonyms: record

5. one of the main divisions of a play or opera:

   the second act of Hamlet.

6. a short performance by one or more entertainers, usually part of a variety show or radio or television program.

   Synonyms: routine, turn

7. the personnel of such a group:

   The act broke up after 30 years.

8. false show; pretense; feint:

   The politician's pious remarks were all an act.

9. Philosophy. (in scholasticism)
   1. activity in process; operation.
   2. the principle or power of operation.
   3. form as determining essence.
   4. a state of realization, as opposed to potentiality.

1. to do something; exert energy or force; be employed or operative:

   He acted promptly in the emergency.

   Synonyms: play, work, function, perform

2. to reach, make, or issue a decision on some matter:

   I am required to act before noon tomorrow.

   Synonyms: play, work, function, perform

3. to operate or function in a particular way; perform specific duties or functions:

   to act as manager.

   Synonyms: play, work, function, perform

4. to produce an effect; perform a function:

   The medicine failed to act.

   Synonyms: play, work, function, perform

5. to behave or conduct oneself in a particular fashion:

   to act well under all conditions.

6. to pretend; feign:

   Act interested even if you're bored.

7. to perform as an actor:

   He acted in three plays by Molière.

8. to be capable of being performed:

   His plays don't act well.

9. to serve or substitute (usually followed by for ):

   In my absence the assistant manager will act for me.

1. to represent (a fictitious or historical character) with one's person:

   to act Macbeth.

   Synonyms: play

2. to feign; counterfeit:

   to act outraged virtue.

3. to behave as:

   He acted the fool.

   Synonyms: play

4. Obsolete. to actuate.

verb phrase

1. 1. to act in accordance with; follow:

      He acted on my advice.

   2. to have an effect on; affect:

      The stirring music acted on the emotions of the audience.

2. 1. to demonstrate or illustrate by pantomime or by words and gestures:

      The party guests acted out stories for one another.

   2. Psychology. to give overt expression to (repressed emotions or impulses) without insightful understanding:

      The patients acted out early traumas by getting angry with the analyst.

3. Informal. to organize one's time, job, resources, etc., so as to function efficiently:

   The new administration is still getting its act together.

4. 1. to fail to function properly; malfunction:

      The vacuum cleaner is acting up again.

   2. to behave willfully:

      The children always act up in school the day before a holiday.

   3. to become painful or troublesome, especially after a period of improvement or remission:

      My arthritis is acting up again this morning.

1. Trademark. a standardized college admissions test developed by ACT, Inc., measuring English, mathematics, reading, and science skills: originally an abbreviation of American College Testing/American College Test. Compare SAT.
2. Association of Classroom Teachers.
3. Australian Capital Territory.

1. acting.
2. active.
3. actor.
4. actual.