C14: from Old French aseürer to assure, from Medieval Latin assēcūrāre to secure or make sure, from sēcūrussecure
Word Origin and History for assured
adj.
of persons, "confident, self-assured," late 14c., past participle adjective from assure. Related: Assuredly; assuredness.
assure
v.
late 14c., from Old French asseurer (12c., Modern French assurer) "to reassure, calm, protect, to render sure," from Vulgar Latin *assecurar, from Latin ad- "to" (see ad-) + securus "safe, secure" (see secure (adj.)). Related: Assured; assuring.