crownwork

from The Century Dictionary.

• noun In dentistry, the attachment of an artificial crown of gold or porcelain to the root of a tooth.
• noun In fortification, an outwork running into the field, consisting of two demi-bastions (a a) at the extremes, and an entire bastion in the middle, with curtains (c c). It is designed to secure a hill or other advantageous post and cover the other works.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Fort.) A work consisting of two or more bastioned fronts, with their outworks, covering an enceinte, a bridgehead, etc., and connected by wings with the main work or the river bank.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A type of fortification, like a hornwork, but consisting of a full bastion with the walls on either side ending in half-bastions from which longer flank walls run back towards the main fortress.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (dentistry) dental appliance consisting of an artificial crown for a broken or decayed tooth