water rat

from The American Heritage® Dictionary of the English Language, 4th Edition

• n. Any of various semiaquatic rodents, especially Neofiber alleni, of Florida and southern Georgia, closely related to and resembling the muskrat.
• n. See muskrat.
• n. Slang A petty thief or ruffian who frequents waterfronts.

from Wiktionary, Creative Commons Attribution/Share-Alike License

• n. Any of various rodents from Florida and southern Georgia, especially Neofiber alleni; the muskrat.
• n. The Eurasian water vole, Arvicola amphibius (or Arvicola terrestris).
• n. A petty thief or waterfront ruffian.
• n. A person fond of water sports.
• n. A member of the water police.

from the GNU version of the Collaborative International Dictionary of English

• The water vole. See under vole.
• The muskrat.
• The beaver rat. See under beaver.
• A thief on the water; a pirate.

from The Century Dictionary and Cyclopedia

• n. One of several different rodents, of aquatic habits, belonging to the family Muridæ.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• n. any of various amphibious rats
• n. a person who enjoys being in or on the water
• n. common large Eurasian vole