What's the "een" in Halloween?
magic bullet mag·ic bullet (māj'ĭk)
A drug, therapy, or preventive therapy that cures or prevents a disease.
A miraculous remedy for some social, economic, etc, ill: We know no one chancellor has a magic bullet to turn the school system around
[1960s+; fr the name given in 1910 to salvarsan, formerly a trademark, discovered and proposed by the bacteriologist Paul Ehrlich as a cure for syphilis]
A very effective, quasi-magical agent, remedy, etc: Stokovich looked on Kennedy as his ''silver bullet,'' his absolute best man/ No single silver bullet is going to do the job
[1808+; reflecting an ancient belief that silver weapons can conquer any foe, found, for example, in the Delphic Oracle's advice to Philip of Macedon, ''With silver weapons you may conquer the world'']
(Or "silver bullet" from vampire legends) A term widely used in software engineering for a supposed quick, simple cure for some problem. E.g. "There's no silver bullet for this problem".