The Collaborative International Dictionary of English v.0.48:

Detonation \Det`o*na"tion\ (d[e^]t`[-o]*n[=a]"sh[u^]n), n. [Cf.
   F. d['e]tonation.]
   An explosion or sudden report made by the instantaneous
   decomposition or combustion of unstable substances; as, the
   detonation of gun cotton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

detonation
    n 1: a violent release of energy caused by a chemical or nuclear
         reaction [syn: explosion, detonation, blowup]
    2: the act of detonating an explosive