Certainty \Cer"tain*ty\, n.; pl. {Certainties}. [OF. certainet['e].] 1. The quality, state, or condition, of being certain. The certainty of punishment is the truest security against crimes. --Fisher Ames. 2. A fact or truth unquestionable established. Certainties are uninteresting and sating. --Landor. 3. (Law) Clearness; freedom from ambiguity; lucidity. {Of a certainty}, certainly.