From WordNet (r) 3.0 (2006) [wn]:
avalanche
n 1: a slide of large masses of snow and ice and mud down a
mountain
2: a sudden appearance of an overwhelming number of things; "the
program brought an avalanche of mail"
v 1: gather into a huge mass and roll down a mountain, of snow
[syn: avalanche, roll down]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Avalanche \Av"a*lanche`\ (?; 277), n. [F. avalanche, fr. avaler
to descend, to let down, from aval down, downward; ? (L. ad)
+ val, L. vallis, valley. See Valley.]
1. A large mass or body of snow and ice sliding swiftly down
a mountain side, or falling down a precipice.
[1913 Webster]
2. A fall of earth, rocks, etc., similar to that of an
avalanche of snow or ice.
[1913 Webster]
3. A sudden, great, or irresistible descent or influx of
anything.
[1913 Webster]