• (n.) A lamp with lenses or reflectors to collect the rays of light and throw them in a given direction; -- used in lighthouses.
Hol'o·phote noun A lamp with lenses or reflectors to collect the rays of light and throw them in a given direction; -- used in lighthouses. 
The holophote was a form of lamp in which the light was converged and directed to a particular spot to prevent collisions at sea etc.
holophote 1. A lamp with lenses or reflectors to collect the rays of light and throw them in a given direction; such as, those used in lighthouses. 2. An apparatus by which practically all the light from a lighthouse lamp or the like is thrown in a desired direction.
an apparatus by which practically all the light from a lighthouse lamp or the like is thrown in a desired direction.