/ Dictionary / Index O outwash plain: Meaning and Definition of Find definitions for: out'wash plain" Pronunciation: [key] a broad, sloping landform built of coalesced deposits of outwash. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. outwash outwatch Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language