rampart

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A fortification consisting of an embankment, often with a parapet built on top.
2. n. A means of protection or defense; a bulwark. See Synonyms at bulwark.
3. v. To defend with a rampart.

Century Dictionary and Cyclopedia

1. n. In fortification, an elevation or mound of earth round a place, capable of resisting cannon-shot, and having the parapet raised upon it; a protecting enceinte; also, this elevation together with the parapet. The rampart is built of the earth taken out of the ditch, but the lower part of the outer slope is usually constructed of masonry. The top of the rampart behind the parapet should have sufficient width for the free passage of troops, guns, etc. See cut under parapet.
2. n. Hence Something that serves as a bulwark or defense; an obstruction against approach or intrusion; a protecting inclosure.
3. n. Synonyms See fortification.
4. To fortify with ramparts; protect by or as if by a rampart; bolster; strengthen.

Wiktionary

1. n. A defensive mound of earth or a wall with a broad top and usually a stone parapet; a wall-like ridge of earth, stones or debris; an embankment for defensive purpose.
2. n. A defensive structure; a protective barrier; a bulwark.
3. n. That which defends against intrusion from outside; a protection.
4. n. usually plural A steep bank of a river or gorge.
5. v. To defend with a rampart; fortify or surround with a rampart.

GNU Webster's 1913

1. n. That which fortifies and defends from assault; that which secures safety; a defense or bulwark.
2. n. (Fort.) A broad embankment of earth round a place, upon which the parapet is raised. It forms the substratum of every permanent fortification.
3. v. To surround or protect with, or as with, a rampart or ramparts.

WordNet 3.0

1. n. an embankment built around a space for defensive purposes