The Collaborative International Dictionary of English v.0.48:
Cornice \Cor"nice\ (k?r"n?s), n. [F. corniche, It. cornice, LL.
coronix, cornix, fr. L. coronis a curved line, a flourish
with the pen at the end of a book or chapter, Gr. ???; akin
to L. corona crown. sEE Crown, and cf. Coronis.] (Arch.)
Any horizontal, molded or otherwise decorated projection
which crowns or finishes the part to which it is affixed; as,
the cornice of an order, pedestal, door, window, or house.
Cornice ring, the ring on a cannon next behind the muzzle