Definition of "initiator"
(military) A component of a nuclear weapon that produces a burst of neutrons to trigger a fission chain reaction.
Quotations
‘This, er, initiator of polonium and lithium, would it be used in an anti-personnel bomb?’ he asked. ‘Oh yes, you could say so, boyo,’ replied the Welshman. ‘An initiator, you see, is what sets off a nuke.’
1984, Frederick Forsyth, The Fourth Protocol, London: Hutchinson, page 301