Wordnet 3.0
NOUN (1)
1. 
 a simple guaranteed solution for a difficult problem; 
- Example: "no silver bullet can make the world safe from terrorism"
WordNet (r) 3.0 (2006):
silver bullet
    n 1: a simple guaranteed solution for a difficult problem; "no
         silver bullet can make the world safe from terrorism"
The Free On-line Dictionary of Computing (30 December 2018):
magic bullet
silver bullet
    (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".
   (1999-01-13)