Acting meaning : To do something. To do (something); to perform. To perform a theatrical role. Of a play: to be acted out (well or badly). To behave in a certain manner for an indefinite length of time. To convey an appearance of being. To do something that causes a change binding on the doer. (construed with on or upon) To have an effect (on). To play (a role). To feign. (construed with on or upon, of a group) To map via a homomorphism to a group of automorphisms (of). To move to action; to actuate; to animate. An action or deed. Something done by a party — so called to avoid confusion with the legal senses of deed and action. Pretending. The occupation of an actor. Temporarily assuming the duties or authority of another person when they are unable to do their job.