Definition of: act

(akt) v.t.
1. To play the part of; impersonate, as in a drama: She acted Juliet well.
2. To perform on the stage, as a play: The company acted most of Shaw′s works.
3. To perform as if on a stage; feign the character of: Don't act the martyr.
4. To behave as suitable to: Act your age.
5. Obs. To actuate.
—v.i.
5. To behave or conduct oneself: He knows how to act in society.
6. To carry out a purpose or function; perform: The brake refused to act.
7. To carry out a purpose or function in a particular way: with as: The test acted as a check.
8. To put forth power; produce an effect: often with on: The poison acted on his stomach at once.
9. To serve temporarily or as a substitute, as in some office or capacity: with for: The corporal acted for her commanding officer.
10. To perform on or as on the stage: She acts for a living.
11. To pretend; play a part so as to appear: He concealed his real feelings and acted friendly.
12. To serve for theatrical performance or use: This scene acts well.
—to act on (or upon) To order one's conduct in accordance with; obey: to act on someone's advice.
—to act up Colloq. To behave mischievously; appear troublesome. [<L actus. pp. of agere do, infl. in development by the n.]
—noun
1. The exertion of power, bodily or mental; something done; a deed.
2. A section of a drama; the largest division of a play or opera.
3. An enactment or edict; a formal transaction, as of a legislative body.
4. A formal written statement.
5. The performance of a natural function or process. [<L actus a doing, and actum a thing done < agere do] Synonyms (noun): accomplishment, achievement, action, consummation, deed, doing, effect, execution, exercise, exertion, exploit, feat, motion, movement, operation, performance, proceeding, transaction, work. Act is single, individual, momentary; action a complex of acts, or a process, state, or habit of exerting power. Act and deed are both used for the thing done, but act refers to the power put forth, deed to the result accomplished. Deed is commonly used of great, notable, and impressive acts, as are achievement, exploit, and feat. A feat exhibits strength, skill, personal power, whether mental or physical; as, a feat of arms, a feat of memory. Achievement is the doing of something great and noteworthy; an exploit is brilliant, but its effect may be transient; an achievement is solid, and its effect enduring. See EXERCISE, MOTION. Antonyms: cessation, deliberation, endurance, immobility, inaction, inactivity, inertia, passion (in philosophic sense), quiescence, quiet, repose, rest, suffering, suspension.