/ik sploh"zheuhn/ , n.
1. an act or instance of exploding; a violent expansion or bursting with noise, as of gunpowder or a boiler (opposed to implosion ).
2. the noise itself: The loud explosion woke them.
3. a violent outburst, as of laughter or anger.
4. a sudden, rapid, or great increase: a population explosion.
5. the burning of the mixture of fuel and air in an internal-combustion engine.
6. Phonet. plosion.
[ 1615-25; explosion- (s. of explosio ), equiv. to explos ( us ) driven off by clapping (ptp. of explodere to EXPLODE) + -ion- -ION ]