Source : Webster's Revised Unabridged Dictionary (1913)

Lunette \Lu*nette"\, n. [F., dim. of lune moon, L. luna. See
   {Lune} a crescent.]
   1. (Fort.) A fieldwork consisting of two faces, forming a
      salient angle, and two parallel flanks. See {Bastion}.

   2. (Far.) A half horseshoe, which wants the sponge.

   3. A kind of watch crystal which is more than ordinarily
      flattened in the center; also, a species of convexoconcave
      lens for spectacles.

   4. A piece of felt to cover the eye of a vicious horse.

   5. (Arch.) Any surface of semicircular or segmental form;
      especially, the piece of wall between the curves of a
      vault and its springing line.

   6. An iron shoe at the end of the stock of a gun carriage.

   {Lunette window} (Arch.), a window which fills or partly
      fills a lunette.

Source : WordNet®

lunette
     n 1: temporary fortification like a detached bastion
     2: oval or circular opening; to allow light into a dome or
        vault [syn: {fenestella}]