surefire
adjective

- certain to succeed

Oxford Dictionary

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The adjective surefire is a blend of sure (certain, without any doubt) and fire, as in a weapon like a rifle. This term originally referred to the accuracy of a rifle and the person shooting it. It meanwhile is used mainly in a figurative sense to describe something that is certain to happen or succeed.

Another surefire way to expand your English vocabulary is to remember these other expressions that use the word "sure":

- a sure thing/sure bet = something that is certain to happen (It's a sure thing she will be promoted)

- sure enough = actually, as one might have thought (Sure enough, she was promoted to sales manager)

- make sure = to make certain (Make sure you lock the door when you leave)

- to be sure = without doubt, of course (The car is very expensive, to be sure, but the quality is excellent)

- sure as hell = absolutely certain (I sure as hell won't talk to him anymore!)

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SYNONYMS

airtight, certain, foolproof, guaranteed, perfect, reliable, unassailable, unerring

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Practice OWAD in a conversation

"Our new campaign will be a SUREFIRE success."