Results

Definition of certainty : 1. A fact or truth unquestionable established.
2. Clearness; freedom from ambiguity; lucidity.
3. The quality, state, or condition, of being certain.

Synonyms:

matter of course, induction, evidence, a safe bet, foregone conclusion, beyond (any) doubt, demonstration, belief, persuasion, self-assurance, hunch, inevitability, satisfaction, cinch, sure thing, firm/safe ground, deduction, consequence, ineluctability, a foregone conclusion, a mathematical certainty, inevitableness, positiveness, certain, firmness, true, reality, result, suspect, face, guarantee, assuredness, self-confidence, gut feeling/instinct, conclusion, doubtlessness, inference, cocksureness

conviction, assurance, sureness, faith, irrefutability, surety, certitude, confidence, trust

authenticity, veracity, fact, proof, gospel, honesty, verity, rightness, matter-of-factness, truth, absoluteness, axiom, definiteness

reliability, faithfulness, trustworthiness, trusty, devotion, loyalty, dependability, conscientiousness

Usage examples:

• In my place, I know to a certainty, Ernest, you'd have done exactly as I did. - "The Beckoning Hand and Other Stories The Beckoning Hand--Lucretia--The Third Time--The Gold Wulfric--My Uncle's Will--The Two Carnegies--Olga Davidoff's Husband--John Cann's Treasure--Isaline and I--Professor Milliter's Dilemma--In Strict Confidence--The ", Grant Allen.
• And he was such a certainty to me. - "The Complete Project Gutenberg Works of George Meredith", George Meredith.
• There was a reason for this certainty, right or wrong, in the minds of the sealers. - "Masters of the Wheat-Lands", Harold Bindloss.