Gaffer Tape A cloth tape with a flat finish that can be used to temporarily fix cable in place. It is also useful for covering seams in flats that are joined together to form a wall because the surface is easy to paint and doesn't reflect light.
Gaffer Chief electrician in charge of lighting.
Gallery In 19th century theatre, the highest and cheapest seats in the house; often consisting of simple benches without backs. Those who occupied the gallery were sometimes referred to as "the gods", and were often among the more perceptive members of the audience. Ultimately the term "the gods" came to refer to the gallery itself.
Gauze A drop made of mesh netting that is used to simulate glass and in scrims.
Gel A thin sheet of colored plastic (originally gelatin -- hence the name) that is placed in a gel frame and inserted in a lighting instrument to add color to the beam of light. Careful use of gels in a lighting plot can play a major role in setting the emotional mood of scene.
Gel Frame See, Color Frame.
Ghost Light The light, usually by the stage door, that is always left burning. It is supposed to please the ghosts of the theatre, and keep them company.
Gobo A thin metal disc that can be inserted in the "gate" of an ellipsoidal lighting instrument by means of a gobo holder. The disc has a pattern cut into that can be used to project the pattern via the beam of light to create effects such as lightning bolts, the shadows of trees, etc.
Grand Drape The "main" curtain or drape separating the stage from the audience.
Grease-Paint Term for make-up with an oil or "grease" base. Grease-paint sticks replaced powder based makeup after their invention in the 1860's by Ludwig Leichner, a Wagnerian opera-singer.
Green Room Room or space near the stage, used by actors and crew between acts or while waiting to go on.
Grid The metal or wooden framework or gridiron suspended above the stage on which headblocks and pulleys are mounted through which are run the lines used to fly scenery, drops and lighting battens.
Grip Stagehand. A member of the stage crew who moves and sets up pieces of scenery and props before a show and during scene changes.
Ground Plan The plan of for a set. Similar to a blueprint, showing walls, doors, and the placement of scenery, furniture and the like.
Ground Row Masking element of flats or low platforms used to mask the bottom of a cyclorama or rear wall of a set and hide the strips of lighting instruments used to illuminate them.
Gusset A brace, usually triangular, used to reinforce the corners and crosspiece connections in a flat frame. Can also be used to "scab" flats together to form a wall on a box set.