Source : Webster's Revised Unabridged Dictionary (1913)

Projector \Pro*jec"tor\, n.
   An optical instrument for projecting a picture upon a screen,
   as by a magic lantern or by an instrument for projecting (by
   reflection instead of transmission of light) a picture of an
   opaque object, as photographs, picture post-cards, insects,
   etc., in the colors of the object itself. In this latter form
   the projection is accomplished by means of a combination of
   lenses with a prism and a mirror or reflector. Specific
   instruments have been called by different names, such as
   {radiopticon}, {mirrorscope}, {balopticon}, etc.

Projector \Pro*ject"or\, n. [Cf. F. projeteur.]
   One who projects a scheme or design; hence, one who forms
   fanciful or chimerical schemes. --L'Estrange.

Source : WordNet®

projector
     n 1: an optical device for projecting a beam of light
     2: an optical instrument that projects an enlarged image onto a
        screen