/ Dictionary / Index A alluvial fan: Meaning and Definition of Find definitions for: allu'vial fan' Pronunciation: [key] — Physical Geog. Physical Geog. a fan-shaped alluvial deposit formed by a stream where its velocity is abruptly decreased, as at the mouth of a ravine or at the foot of a mountain. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. alluvial alluvial plain Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language