An action

action, deed, performance, exploit; see action 2.

An official or legal statement

law, proposal, judgment, commitment, verdict, amendment, order, announcement, edict, ordinance, decree, statute, writ, bull, warrant, summons, subpoena, document, bill, code, clause, law of the land*.

A division of a play

scene, curtain, prologue, epilogue, introduction, entr'acte, interlude, finale, unit of dramatic action.

A short performance in a show

routine, performance, number, bit, sketch, skit, monologue, curtain raiser, appearance, turn, stand-up routine, shtick*.

A pose

falsification, feigning, affectation, pose; see pose, pretense 1.

To perform an action

do, execute, carry out, carry on, perform, operate, transact, accomplish, achieve, consummate, carry into effect, perpetrate, persevere, persist, labor, work, run, function, officiate, preside, serve, go ahead, take action, go about, step into, take steps, play a part, take a part, begin, move, proceed, enforce, maneuver, be in process, be in action, create, practice, deal in, prosecute, develop, make progress, be active, take effect, produce an effect, commit, fight, combat, respond, keep going, answer, pursue, put forth energy, hustle*, get going*, pull*, do one's stuff*, get down to brass tacks*; see also perform 1.

Antonyms wait*, await*, rest. *

To conduct oneself

behave, seem, appear, carry oneself, acquit oneself, comport oneself, bear oneself, handle oneself, demean oneself, give the appearance of, represent oneself as, take on, play one's part, impress one as, cut a figure*; see also behave 2.

To play a role in or as if in a play

perform, play, playact, impersonate, personate, represent, enact, act out, simulate, live over, pretend, mimic, mime, pantomime, burlesque, parody, feign, fake, portray, render the role of, create a role, rehearse, take a part, dramatize, star, spout, rant, declaim, overact, play the part of, act the part of, make one's debut, masquerade as, put on airs*, put on an act*, tread the boards*, strut one's stuff*, ham*, emote*, mug*, chew the scenery*, throw a performance*; see also pretend 1, 2.