Ellipsis of Act of Parliament.

Initialism of Australian Capital Territory, a federal territory of Australia. / Initialism of American College Test.

An instance of a certain standardized college admissions test in the United States, originally called the American College Test.

(countable) Something done, a deed. / (obsolete, uncountable) Actuality. / (theology) Something done once and for all, as distinguished from a work.

(intransitive) To do something. / (obsolete, transitive) To do (something); to perform. / (intransitive) To perform a theatrical role. / (intransitive) Of a play: to be acted out (well or badly).

Temporarily assuming the duties or authority of another person when they are unable to do their job.

present participle of act

(countable, obsolete) An action or deed. / (law) Something done by a party — so called to avoid confusion with the legal senses of deed and action. / Pretending. / (drama) The occupation of an actor.

(biblical) Clipping of Acts of the Apostles.

plural of Act.