Detonator (noun)

1. A device or substance used to initiate the explosion of a charge of explosives.
2. Something that triggers or causes an explosion or sudden release of energy.

Origin:

Late 19th century: from french détonateur, from détoner "to detonate", from de- (expressing reversal) + toner "to thunder".

Examples:

1. The bomb was fitted with a simple electrical detonator.
2. The researchers discovered a chemical detonator that could trigger a chain reaction.
3. The detonator was carefully placed to bring down the building.
4. The scientists were experimenting with new types of detonators.
5. The detonator was the final piece that was needed to complete the experiment.