The Collaborative International Dictionary of English v.0.48:

Lantern \Lan"tern\ (l[a^]n"t[~e]rn), n. [F. lanterne, L.
   lanterna, laterna, from Gr. lampth`r light, torch. See
   Lamp.]
   1. Something inclosing a light, and protecting it from wind,
      rain, etc.; -- sometimes portable, as a closed vessel or
      case of horn, perforated tin, glass, oiled paper, or other
      material, having a lamp or candle within; sometimes fixed,
      as the glazed inclosure of a street light, or of a
      lighthouse light.
      [1913 Webster]

   2. (Arch.)
      (a) An open structure of light material set upon a roof,
          to give light and air to the interior.
      (b) A cage or open chamber of rich architecture, open
          below into the building or tower which it crowns.
      (c) A smaller and secondary cupola crowning a larger one,
          for ornament, or to admit light; such as the lantern
          of the cupola of the Capitol at Washington, or that of
          the Florence cathedral.
          [1913 Webster]

   3. (Mach.) A lantern pinion or trundle wheel. See Lantern
      pinion (below).
      [1913 Webster]

   4. (Steam Engine) A kind of cage inserted in a stuffing box
      and surrounding a piston rod, to separate the packing into
      two parts and form a chamber between for the reception of
      steam, etc.; -- called also lantern brass.
      [1913 Webster]

   5. (Founding) A perforated barrel to form a core upon.
      [1913 Webster]

   6. (Zool.) See Aristotle's lantern.
      [1913 Webster]

   Note: Fig. 1 represents a hand lantern; fig. 2, an arm
         lantern; fig. 3, a breast lantern; -- so named from the
         positions in which they are carried.
         [1913 Webster]

   Dark lantern, a lantern with a single opening, which may be
      closed so as to conceal the light; -- called also
      bull's-eye.

   Lantern jaws, long, thin jaws; hence, a thin visage.

   Lantern pinion, Lantern wheel (Mach.), a kind of pinion
      or wheel having cylindrical bars or trundles, instead of
      teeth, inserted at their ends in two parallel disks or
      plates; -- so called as resembling a lantern in shape; --
      called also wallower, or trundle.

   Lantern shell (Zool.), any translucent, marine, bivalve
      shell of the genus Anatina, and allied genera.

   Magic lantern, an optical instrument consisting of a case
      inclosing a light, and having suitable lenses in a lateral
      tube, for throwing upon a screen, in a darkened room or
      the like, greatly magnified pictures from slides placed in
      the focus of the outer lens.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lantern wheel
    n 1: a small pinion having cylindrical bars instead of teeth,
         used chiefly in inexpensive clocks [syn: lantern pinion,
         lantern wheel]