certainty

n.

1. Firmness of belief

   certitude, assurance, conviction, confidence, sureness, faith, positiveness, definiteness, authoritativeness, firmness, persuasion, surety, self-confidence, self-assurance, cocksureness, indisputability, incontestability, irrefutability, unquestionableness; see also belief 1, faith 1.

2. Something looked upon as certain

   fact, truth, foregone conclusion, sure thing*; see fact 1, reality 1, result, truth 1.

certainty suggests a firm, settled belief or positiveness in the truth of something; certitude is sometimes distinguished from the preceding as implying an absence of objective proof, hence suggesting unassailable blind faith; assurance suggests confidence, but not necessarily positiveness, usually in something that is yet to happen feel no assurance of his continuing support; conviction suggests a being convinced, as of the truth of a belief, because of satisfactory reasons or proof and sometimes implies earlier doubt