searchlight

noun

1. a device, usually consisting of a light and reflector, for throwing a beam of light in any direction.
2. a beam of light so thrown.

noun

1. a device, consisting of a light source and a reflecting surface behind it, that projects a powerful beam of light in a particular direction
2. the beam of light produced by such a device

n.also search-light, 1882, from search (v.) + light (n.).