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.

• (architecture) a small circular or crescent-shaped opening in a vaulted roof
  
• (architecture) a crescent-shaped recess or void space above a window or door
  
• a field work consisting of two projecting faces forming a wedge each of which extends from one of two parallel flanks
  
• (geology) (the shape of) a crescent-shaped dune
  
• goggles for swimming under water
  
• (Christianity) a crescent-shaped clip for holding the host upright when exposed in the monstrance