cuirass

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A piece of armor for protecting the breast and back.
2. n. The breastplate alone.
3. n. A defense or protection: "A carefully primped irony, that cuirass of art in the early Eighties, is necessary—a distance so affected as to constitute a hopeless impediment to feeling” ( Robert Hughes).
4. n. Zoology A protective covering of bony plates or scales.
5. v. To protect with a cuirass.

Century Dictionary and Cyclopedia

1. n. A piece of defensive armor covering the body from the neck to the girdle, and combining a breastplate and a backpiece. Such a protection was used among the ancients in various forms, but under different names (see breastplate, thorax), and is still worn by the heavy cavalry specifically called cuirassicrs in the French and other European armies. The cuirass seems to have been first adopted in England in the reign of Charles I., when the light cavalry were armed with buff coats, having the breast and back covered with steel plates. Subsequently this piece of armor fell into disuse, and was resumed by the English only after the battle of Waterloo, where the charges of the French cuirassiers were very effective.
2. n. Any similar covering, as the protective armor of a ship; specifically, in zoology, some hard shell or other covering forming an indurated defensive shield, as the carapace of a beetle or an armadillo, the bony plates of a mailed fish, etc.

Wiktionary

1. n. A piece of defensive armor, covering the body from the neck to the girdle.
2. n. The breastplate taken by itself.

GNU Webster's 1913

1. n. A piece of defensive armor, covering the body from the neck to the girdle.
2. n. The breastplate taken by itself.
3. n. An armor of bony plates, somewhat resembling a cuirass.

WordNet 3.0

1. n. medieval body armor that covers the chest and back