late 14c., "formal or solemn pledge, promise," also "certainty," from Old French asseurance (11c., Modern French assurance) "assurance, promise; truce; certainty, safety, security," from asseurer (see assure). The word had a negative tinge 18c., often suggesting impudence or presumption.
1. The EU is now acquiring greater assurance and authority.
2. They had given an absolute assurance that it would be kept secret.
3. Masur led the orchestra with assurance.
4. The young teacher lacked assurance in front of his class.
5. Progress is the activity of today and the assurance of tomorrow.