assurance

freedom from doubt; belief in yourself and your abilities; "his assurance in his superiority did not make him popular"; "after that failure he lost his confidence"; "she spoke with authority"
a statement intended to inspire confidence; "the President''s assurances were not respected"
a binding commitment to do or give or refrain from something; "an assurance of help when needed"; "signed a pledge never to reveal the secret"
a British term for some kinds of insurance