n. One who or that which illuminates or gives light; a natural or artificial source of light, literally or figuratively: as, the sun is the primary illuminator.n. One who decorates manuscripts, books, etc., with ornamental pictures, designs, letters, etc., in the style called illumination.n. A lens or mirror in a microscope or other optical instrument for concentrating the light.n. A glass tile or floor-light.n. An apparatus for directing a beam of light upon some object, as in lighting parts of the body in surgical or medical examinations.n. A device for carrying a small electric light into the mouth in examining the teeth.