Definition from Wiktionary, the free dictionary
detonator (plural detonators)
- A device used to detonate an explosive device etc.
- (rail transport, UK) a small explosive device attached to the railhead to provide an audible warning when a train passes over it.
- (rail transport): torpedo (US)
Related terms 
device used to detonate an explosive device
rail transport: small explosive arning device
See also 
- (device for detonating explosives): blasting cap