1) Imaginary stage front 
These are the selected anniversaries for November that appear on the India portal. The `edit` links edit the portal subpages that are displayed as sections here. ==November 1== ==November 2== ==November 3== ==November 4== ==November 5== ==November 6== ==November 7== ==November 8== ==November 9== ==November 10== ==November 11== ==November 12== ==..... The fourth wall is the imaginary `wall` at the front of the stage in a traditional three-walled box set in a proscenium theatre, through which the audience sees the action in the world of the play. The idea of the fourth wall was made explicit by philosopher and critic Denis Diderot and spread in 19th-century theatre with the advent of theatrica.....
The imaginary wall of the box theater setting, supposedly removed to allow the audience to see the action. The fourth wall is especially common in modern and contemporary plays such as Hansberry's A Raisin in the Sun, Wasserstein's Tender Offer, and Wilson's Fences.
(from the article `theatre`) ...speak as though they were at home. Antoine is normally credited with being the first to require an actor to turn his back on the audience; from ...
An imaginary barrier between the actors who are onstage and the audience who is watching them.
Sometimes referred to as the 'third wall,' depending upon how a stagebuilder numbers the sides of th
The imaginary wall which separates the audience from the stage in a proscenium theatre. 
the imaginary “wall” between actors on stage and the audience.
the invisible wall of a set through which the audience sees the action of the play.
A metaphor for the invisible and imaginary 'wall' between the Actors on stage and the audience
An imaginary wall between the cast and audience which completes the area in which a piece is set.
The imaginary wall which separates the actors from the audience, and the audience from the stage. The actor uses it to create the reality in the scene, and keep one’s mind in the world of the film or play.
Sounds like something from the Twilight Zone but is really the conceptual barrier between actor and audience member
An imaginary wall between the actors and the audience that disallows interaction between the two groups of people. See also proscenium.
the imaginary wall of a box set, separating the actors from the audience.
The imaginary plane that separates the characters and action of the film from the viewing audience.