1. The act of exploding; detonation; a chemical action which causes the sudden formation of a great volume of expanded gas; as, the explosion of gunpowder, of fire damp,etc.
2. a bursting with violence and loud noise, because of internal pressure; as, the explosion of a gun, a bomb, a steam boiler, etc.
3. a violent outburst of feeling, manifested by excited language, action, etc.; as, an explosion of wrath. A formidable explosion of high-church fanaticism. (Macaulay)
4. a sudden increase, proliferation, appearance or outbreak, as in population explosion, Cambrian explosion of animal forms, explosion of colour
Origin: L. Explosio a driving off by clapping: cf. F. Explosion explosion. See explode.