assurance (n.)youdaoicibaDictYouDict[assurance 词源字典]
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.[assurance etymology, assurance origin, 英语词源]