disintegration

Short definition from Wiktionary

Noun

1. 1
   A process by which anything disintegrates.
2. 2
   The condition of anything which has disintegrated.
3. 3
   The wearing away or falling to pieces of rocks or strata, produced by atmospheric action, frost, ice, etc.
4. 4
   The process of radioactive decay.
5. 5
   The process of radioactive decay: The radioactive decay of a single atom.