The Collaborative International Dictionary of English v.0.48:
Rerebrace \Rere"brace`\ (r?r"br?s"), n. [F. arri?re-bras.] (Anc. Armor) Armor for the upper part of the arm. --Fairholt. [1913 Webster]WordNet (r) 3.0 (2006):
rerebrace n 1: cannon that provides plate armor for the upper arm [syn: rerebrace, upper cannon]