Above An anachronistic stage direction, assumed to mean entrance from a practical upper level of the stage.
Act A unit or division of a play, each of which is composed of one or more scenes. Originally, Greek plays were continuous and the introduction of divisions was a later development. Plays today may divided into one, two, or three acts.
Act Curtain Also referred to as an Act-Drop, the term refers to a curtain or painted cloth which was closed or opened to signify the beginning or ending of an act, as distinguished from the main curtain or grand drape.
Action The movement or development of the plot, or story in a play.
Aesthetic Values Lighting, costumes, sets or other elements that make-up the production's sense of beauty and style.
Antagonist The opponent or adversary of the hero or protaganist of a drama.
Apron The area of the stage extending beyond the proscenium.
Arena The area of a play's action in "theaters in the round", in which the audience sits surrounding the stage.
Aria An operatic term denoting a highly formalized musical structure that expresses feeling or emotion rather than conveying information or advancing the action of a drama.
Aside Sometimes referred to as breaking the proscenium or breaking the fourth wall, the term refers to a speech or comment made by an actor directly to the audience about the action of the play or another character. The audience is to understand that this comment is not heard or noticed by the other characters in the play.
Audition A trial run or "tryout" for a particular part in a play. In earlier theater, actors were often engaged on the basis of hearsay or their performance in other productions, with auditions coming into vogue in the latter part of the 19th century.
Auditorium Description of the area of a theater seating or accomodating the audience or people witnessing the production. The term, in its present meaning, first came into popular use in the early to mid 16th century.
Aulaeum (archaic) Another term for the curtain -- primarily the main curtain, grand drape or "house curtain" -- separating the audience from the stage.