overhead projector(projector that projects an image over the heads of the viewers onto a screen) noun [UK: ˌəʊv.ə.ˈhed prə.ˈdʒek.tə(r)] [US: ˌoʊv.ə.ˈhed prə.ˈdʒek.tər]
slide projector(a device that projects an enlarged image of a photographic slide onto a screen) noun