pro·jec·tor / prəˈjektər/ • n. 1. an object that is used to project rays of light, esp. an apparatus with a system of lenses for projecting slides or film onto a screen.2. archaic a person who plans and sets up a project or enterprise. ∎  a promoter of a dubious or fraudulent enterprise.

projector Instrument with a lens system, used to cast images onto a screen from an illuminated flat object. An episcope is a projector for opaque objects such as a printed page; it uses light that is reflected from the object. A diascope is a projector for transparent objects such as photographic slides and films; it uses light transmitted through the object. An epidiascope can project images from both transparent and opaque objects. A motion-picture or cine projector produces moving images from many frames (pictures) on a transparent film.