/ Dictionary / Index A ash flow: Meaning and Definition of Find definitions for: ash' flow" Pronunciation: [key] — Geol. Geol. an avalanche of volcanic ash. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ash fall ash gray Related Content Daily Word Quiz: lunar Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language