Ins and Outs of the Stage Vocabulary

On Stage- not on stage so not visible to the audience
Off Stage- on stage so visible to the audience
Wings- the sides of a theatre stage out of view from the audience
Line of Sight- a normally unobstructed line-of-sight between an intended observer (or spectator)(i.e. audience) and a stage, arena or monument.
Cyclorama- a circular picture of a 360˚ scene, viewed from inside
Back Cloth- 
Trap Door- a hinged or removable panel in a floor, ceiling, or roof, usually used for surprise entrances and exits.
House Curtain- curtains at the very front of the stage
Curtain Call- the appearance of one or more performers on stage after a performance to acknowledge the audience's applause.
Fine Curtain- 
Curtain Line- the line marking the position of the curtain when closed

Backstage- in or around the area behind the stage in a theatre, esp. the wings or dressing rooms.
Scenery Dock- 
Bump In/Out- the process or preparing the theatre for a particular production or packing up the theatre after a production. It includes building the set, introducing props and costumes, and rigging the lights.
Calls- 
Dressing Rooms- a room in which performers before, after, or during their performance.
Wardrobe Room- 
Green Room- a room in the theatre in which performers can relax when they are not performing.