The Collaborative International Dictionary of English v.0.48:
bastardise \bastardise\ v. t. Same as bastardize. [chiefly Brit.] [PJC]WordNet (r) 3.0 (2006):
bastardise v 1: change something so that its value declines; for example, art forms [syn: bastardize, bastardise] 2: declare a child to be illegitimate [syn: bastardize, bastardise]