Wiktionary
n. A switch, usually one on a wall in a building, used to turn on or off the light.
Wikipedia
In building wiring, a light switch is a switch, most commonly used to operate electric lights, permanently connected equipment, or electrical outlets. Portable lamps such as table lamps will have a light switch mounted on the socket, base, or in-line with the cord. Manually operated on/off switches may be substituted by remote control switches, or light dimmers that allow controlling the brightness of lamps as well as turning them on or off. Light switches are also found in flashlights and automobiles and other vehicles.
Usage examples of "light switch".
He drifted through the darkness searching for a light switch or a call button.
Although Dylan wanted to do this about as much as he wanted to wrestle a crocodile, he edged into the open doorway, reached around the casing into the room, and felt the wall for the light switch.
Rebecca stood by the light switch, a fuzzy blue dressing gown belted around her, her hair an even more unruly mass of curls than usual.
I flipped the light switch on, then closed the padlock on an inside hasp, locking the door from within.
Strong gave me an interesting idea for a light switch this morning.
The off position stops any signal from traveling through the wire as surely as if you turned off an electric light switch.
I found the hall light switch and turned on the overhead chandelier.
Apart from the dead men the only other objects in that cave were the light fitting and the light switch, and both were made of bakelite.
Dazed and sick I pushed myself wearily to my feet, located a light switch and clicked it with my shoulder.