The quality of being absolutely certain or sure about something; complete confidence or conviction.
From Latin 'certitudo' (certainty), derived from 'certus' (certain, fixed, determined). The word entered English through Old French and has meant absolute confidence since the 14th century.
Certitude is rarely found in science—scientists prefer 'confidence intervals' and 'probability'—because certitude is the enemy of discovery; the moment you feel absolutely certain, you stop questioning.
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