The name of a guitar device invented by Godley and Creme of 10cc fame. More formally called the Gizmotron.
The Gizmo strapped onto the bridge of the guitar. Originally it was designed to make the guitar sound like the string section of an orchestra: The right hand would press Gizmo keys to "bow" the strings, and the left could wander the fretboard as usual. In messing with the Gizmo, Godley & Creme also discovered it could be used for other noises including brass, percussion, and weird sound effects.
The duo left 10cc around 1976 to concentrate on developing and marketing the Gizmo. The prototype was built with the help of John McConnell of the University of Manchester Institute of Science and Technology, who helped perfect a more natural-sounding decay for it. G&C also dove into a three-album project, "Consequences," that was intended to show off what the little device could do.
The Gizmo got great moral support from people including Jimmy Page and Paul McCartney, who apparently plays one on "I'm Carrying," the B-side to his "Londontown" single. Phil Manzanera also put it on one or two of his albums.
But as far as I know, both "Consequences" and the Gizmo were failures, although G&C continued using Gizmo guitars on their albums through 1981. The Gizmo by now is outdated, I'm guessing, thanks to e-bows, synthesizers and MIDI.