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water rat

American  

noun

  1. any of various rodents having aquatic habits.

  2. the muskrat, Ondatra zibethica.

  3. (in Australia and New Guinea) any of the aquatic rats of the subfamily Hydromyinae, especially of the genus Hydromys.

  4. Slang. a vagrant or thief who frequents a waterfront.

water rat British  

noun

  1. any of several small amphibious rodents, esp the water vole or the muskrat

  2. any of various amphibious rats of the subfamily Hydromyinae, of New Guinea, the Philippines, and Australia

  3. informal a person who is very fond of water sports

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of water rat

First recorded in 1545–55

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.