The Collaborative International Dictionary of English v.0.48:
Water vole \Wa"ter vole`\ (Zool.) See under Vole. [1913 Webster]WordNet (r) 3.0 (2006):
water vole n 1: common large Eurasian vole [syn: water vole, water rat, Arvicola amphibius] 2: of western North America [syn: water vole, Richardson vole, Microtus richardsoni]