av·a·lanche (?v??-l?nch?)n.1. A fall or slide of a large mass of material, especially of snow, down a mountainside.2. A massive or overwhelming amount; a flood: received an avalanche of mail.v. av·a·lanched, av·a·lanch·ing, av·a·lanch·es v.intr. To fall or slide in a massive or overwhelming amount.v.tr. To overwhelm; inundate.[French; akin to Provençal lavanca, ravine, perhaps ultimately from Latin l?b?, to slip.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.avalanche (?æv??l??nt?) n1. (Physical Geography) a. a fall of large masses of snow and ice down a mountainb. a fall of rocks, sand, etc2. a sudden or overwhelming appearance of a large quantity of things: an avalanche of letters. 3. (General Physics) physics a group of ions or electrons produced by a single ion or electron as a result of a collision with some other form of mattervbto come down overwhelmingly (upon)[C18: from French, by mistaken division from la valanche, from valanche, from (northwestern Alps) dialect lavantse; related to Old Provençal lavanca, of obscure origin]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014av?a?lanche (?æv ??lænt?, -?l?nt?) n., v. -lanched, -lanch?ing. n. 1. a mass of snow, ice, etc., detached from a mountain slope and sliding or falling suddenly downward. 2. anything like an avalanche in suddenness and overwhelming quantity: an avalanche of mail. 3. a cumulative ionization process in which the ions and electrons of one generation undergo collisions that produce a greater number of ions and electrons in succeeding generations. v.i. 4. to come down in or like an avalanche. v.t. 5. to overwhelm with a large amount of anything. [1755?65;