Backpiece \Back"piece`\, Backplate \Back"plate`\, n. [Back, n.
or a. + piece, plate. ]
1. A piece, or plate which forms the back of anything, or
which covers the back.
[1913 Webster]
2. Specifically: A piece of plate armor protecting the back;
-- it is worn as part of a cuirass.
[WordNet 1.5] Backrack