avalanche

Short definition from Wiktionary

Noun

1. 1
   A large mass or body of snow and ice sliding swiftly down a mountain side, or falling down a precipice.
2. 2
   A fall of earth, rocks, etc., similar to that of an avalanche of snow or ice.
3. 3
   A sudden, great, or irresistible descent or influx; anything like an avalanche in suddenness and overwhelming quantity.

Verb

1. 1
   To descend like an avalanche.
2. 2
   To come down upon; to overwhelm.
3. 3
   To propel downward like an avalanche.