/ Dictionary / Index W water pill: Meaning and Definition of Find definitions for: wa'ter pill" Pronunciation: [key] — Informal. Informal. a diuretic pill. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. waterpick water pimpernel Related Content Daily Word Quiz: diaphanous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language