1) Gaffer aka the chief electrician: The head of the electrical department, responsible for the design and execution of the lighting plan for a production. Gaffer works closely with the cinematographer. Early films used mostly natural light, which stagehands controlled with large tent cloths using long poles called gaffs (stagehands were often beached sailors or longshoremen, and a gaff is a type of boom on a sailing ship). In 16th Century English, the term "gaffer" denoted a man who was the head of any organized group of laborers.
2) Gel: A thin, tinted plastic-like sheet placed over a light to change the color of the projected light.
3) Giraffe: A mechanically extendable and manipulated boom microphone.
4) Goof: A take of a scene which is not useable in the film, mainly because of an on-camera mistake made by the cast or crew.
5) Greens man: A member of the crew who procures, places, and maintains any vegetation on a set.
6) Grip: In the U.S.A and Canada grip are lighting and rigging technicians who work under the key grip in their own department. Grips work closely with the camera department. The second main function of grip department is to work closely with electrical department as well to create necessary lighting set ups under the direction of director of photography.