/ Dictionary / Index W water milfoil: Meaning and Definition of Find definitions for: wa'ter mil"foil Pronunciation: [key] any of various aquatic plants, chiefly of the genus Myriophyllum, the submerged leaves of which are very finely divided. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. water meter water mill Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language