I recently ran across a very odd word (odd, that is, to those who don’t work in the relevant industries); I quote the OED entry (revised 2016):

gobo

noun²

Originally U.S.

1. Cinematography, Television , and Photography . A dark plate, screen, or mask used to shield a lens from light. Also ( Theatre ): a partial screen or mask used in front of a spotlight to project a shape or image or to reduce the light on stage.

1923 ‘Gobo’ and other utterances..are flung around a studio by camera men.

New York Times 21 October x. 5

1925 Elephant ear , a form of gobo consisting of an upright post with a black card or board suspended at right angles, used to shade the camera lens from overhead light.

Los Angeles Times 29 November b6

[…]

1994 Gobos can produce projected images up to 6m in diameter and can be used in conjunction with colour films, slides or moving images.

Museums Journal January 36/3

2. Cinematography and Audio Technology .…