1 blast, bang, report, burst, boom, clap, crack, eruption, crash, outburst, fulmination; detonation:
The explosion shook the entire house.
2 outburst, outbreak, paroxysm, upheaval, flare-up, eruption, burst, fit, spasm, tantrum, Colloq Brit paddy or paddywhack or paddywack, wax:
The unrest among the people is building up to an explosion.
3 increase, burgeoning or bourgeoning, expansion, welling up, mushrooming:
The population explosion has caused a housing shortage.