retirade

from The Century Dictionary.

• noun In fortification, a kind of retrenchment in the body of a bastion or other work, to which a garrison may retreat to prolong a defense. It usually consists of two faces, which make a reëntering angle.

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

• noun (Fort.) A kind of retrenchment, as in the body of a bastion, which may be disputed inch by inch after the defenses are dismantled. It usually consists of two faces which make a reëntering angle.

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

• noun A kind of retrenchment, as in the body of a bastion, which may be disputed inch by inch after the defenses are dismantled. It usually consists of two faces which make a reentering angle.