surefire

/ˈʃʊrˌfaɪər/
adjective
  1. Certain to succeed or work as expected; very reliable.
    • She has a surefire method for getting stains out of clothes.
    • This recipe is a surefire way to impress your dinner guests.
    • Investing in education is a surefire path to a better future.
Synonyms
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