as·sur·ance / əˈshoŏrəns/ • n. 1. a positive declaration intended to give confidence; a promise: he gave an assurance that work would commence on Wednesday.2. confidence or certainty in one's own abilities. ∎  certainty about something: assurance of faith depends on our trust in God.3. chiefly Brit. insurance, specifically life insurance.

assurance A measure of the confidence that (a) a system complies with its security policy or (b) a feature of a system complies with its security requirement. Assurance may be increased by the use of rigorous design techniques and/or by security evaluation.