/ Dictionary / Index W water rat: Meaning and Definition of Find definitions for: wa'ter rat" Pronunciation: [key] any of various rodents having aquatic habits. the muskrat, Ondatra zibethica. (in Australia and New Guinea) any of the aquatic rats of the subfamily Hydromyinae, esp. of the genus Hydromys. a vagrant or thief who frequents a waterfront. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. water rail water-repellent Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language