The word for today is “GAFFER”.
A gaffer in the motion picture industry is the head of the electrical department. They are responsible for the execution of the lighting plan for a production. An experienced gaffer can coordinate the entire job of lighting, including designing the lighting plan. The job is both technical and creative.
The name derives from the early days of film when they were shot mostly in natural light. Filming stages had canvas roofs and the natural light was controlled and directed by moving large tent cloths, to let in more or less light, using long poles called gaffs. In 16th Century English, the term “gaffer” denoted a man who was the head of any organized group of labourers. So the gaffer is the person in charge of men with long poles. Not quite.
Given knowledge of the time of day and conditions to be portrayed the gaffer will manage all the resources needed, from electrical generators, lights, cable, and rigging to manpower. Gaffers are responsible for knowing how to gel the lights or windows (cover with coloured plastic sheeting) to achieve a variety of effects, such as bringing the dawn as night passes into day. They can re-create the flicker of light as a subway car goes through the station, or the motion of light inside an airplane banking across the sky.
Sometimes the gaffer is titled in the credits as Chief Lighting Technician.
The gaffer works with the director of photography (DP) or, in television, the Lighting Director (LD). The DP/LD is responsible for the overall lighting design, but they may give a little or a lot of latitude to the gaffer on these matters, depending on their working relationship. The gaffer also works closely with the key grip, who is in charge of some of the equipment related to the lighting. And the gaffer will usually have an assistant called a best boy. Other members of the lighting crew are called ‘electricians’ though some may have no electrician knowledge or training and may do things like set up stands or move cables.