The Oxford Thesaurus An A-Z Dictionary of Synonyms - sureadj.

1) certain, assured, convinced, persuaded, positive, definite, unwavering, unswerving, unflinching, steadfast, steady, unshakeable or unshakable, confident, satisfied, undeviating, unfaltering: How can you be so sure in your opinion that Jack did it? I'm sure I've met you before. 2) established, firm, solid, trusty, stable, steadfast, secure, safe, trustworthy, reliable: I never travel without my sure companions, courage and caution. 3) accurate, reliable, dependable, tried and true, unfailing, infallible, foolproof, effective, Colloq sure-fire: A high temperature is a sure sign of illness. 4) certain, inevitable, indubitable, unavoidable, ineluctable, inescapable, guaranteed: He who enters the Devil's Cave meets sure death.