1. 1. A release of mechanical, chemical, or nuclear energy in a sudden and often violent manner with the generation of high temperature and usually with the release of gases.
   2. A violent bursting as a result of internal pressure.
   3. The loud, sharp sound made as a result of either of these actions.
2. A sudden, often vehement outburst: an explosion of rage.
3. A sudden, great increase: a population explosion; the explosion of illegal drug use.
4. Linguistics. See plosion.

[Latin explōsiō, explōsiōn-, a driving off, from explōsus, past participle of explōdere, to drive out by clapping. See explode.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.