'Water mouse' definitions:

Definition of 'Water mouse'

From: GCIDE

Water mouse \Wa"ter mouse`\ (Zool.) Any one of several species of mice belonging to the genus Hydromys, native of Australia and Tasmania. Their hind legs are strong and their toes partially webbed. They live on the borders of streams, and swim well. They are remarkable as being the only rodents found in Australia. [1913 Webster]