The Collaborative International Dictionary of English v.0.48:

Culrage \Cul"rage\ (k?l"r?j), n. [OE. culrage, culrache; prob.
   fr. F. cul the buttok + F. & E. rage; F. curage.] (Bot.)
   Smartweed (Polygonum Hydropiper).
   [1913 Webster]