Source : Webster's Revised Unabridged Dictionary (1913)

Louver \Lou"ver\, Louvre \Lou"vre\, n. [OE. lover, OF. lover,
   lovier; or l'ouvert the opening, fr. overt, ouvert, p. p. of
   ovrir, ouvrir, to open, F. ouvrir. Cf. {Overt}.] (Arch.)
   A small lantern. See {Lantern}, 2
   (a) . [Written also {lover}, {loover}, {lovery}, and
       {luffer}.]



   {Louver} {boards or boarding}, the sloping boards set to shed
      rainwater outward in openings which are to be left
      otherwise unfilled; as belfry windows, the openings of a
      louver, etc.

   {Louver work}, slatted work.

Source : WordNet®

louver
     n : one of a set of parallel slats in a door or window to admit
         air and reject rain [syn: {louvre}, {fin}]