Meaning

• Something done, a deed.

  "an act of goodwill"

• Actuality.

• Something done once and for all, as distinguished from a work.

• A product of a legislative body, a statute.

• The process of doing something.

  "He was caught in the act of stealing."

• A formal or official record of something done.

• A division of a theatrical performance.

  "The pivotal moment in the play was in the first scene of the second act."

• A performer or performers in a show.

  "Which act did you prefer? The soloist or the band?"

• Any organized activity.

• A display of behaviour.

• A thesis maintained in public, in some English universities, by a candidate for a degree, or to show the proficiency of a student.

• A display of behaviour meant to deceive.

  "to put on an act"

Meaning

• To do something.

  "If you don't act soon, you will be in trouble."

• To do (something); to perform.

• To perform a theatrical role.

  "I started acting at the age of eleven in my local theatre."

• Of a play: to be acted out (well or badly).

• To behave in a certain manner for an indefinite length of time.

  "A dog which acts aggressively is likely to bite."

• To convey an appearance of being.

  "He acted unconcerned so the others wouldn't worry."

• To do something that causes a change binding on the doer.

  "act on behalf of John"

• (construed with on or upon) To have an effect (on).

  "Gravitational force acts on heavy bodies."

• To play (a role).

  "He's been acting Shakespearean leads since he was twelve."

• To feign.

  "He acted the angry parent, but was secretly amused."

• (construed with on or upon, of a group) To map via a homomorphism to a group of automorphisms (of).

  "This group acts on the circle, so it can't be left-orderable!"

• To move to action; to actuate; to animate.