as·sure (?-sho?or?)tr.v. as·sured, as·sur·ing, as·sures 1. To inform positively, as to remove doubt: assured us that the train would be on time.2. To cause to feel sure: a gesture that assured her of his devotion.3. To give confidence to; reassure.4. To make certain; ensure: “Nothing in history assures the success of our civilization” (Herbert J. Muller).5. To make safe or secure: “We would rather forgo certain benefits in order to be assured against certain evils” (Alfred E. Smith).6. Chiefly British To insure, as against loss.[Middle English assuren, from Old French assurer, from Vulgar Latin *ass?c?r?re, to make sure : Latin ad-, ad- + Latin s?c?rus, secure; see secure.]as·sur?a·ble adj.as·sur?er, as·sur?or n.Usage Note: Assure, ensure, and insure all mean “to make secure or certain.” Only assure is used with reference to a person in the sense of “to set the mind at rest”: The ambassador assured the prime minister of his loyalty. Although ensure and insure are generally interchangeable, only insure is now widely used in American English in the commercial sense of “to guarantee persons or property against risk.”American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.assure (?????) vb (tr; may take a clause as object) 1. to cause to feel sure or certain; convince: to assure a person of one’s love. 2. to promise; guarantee: he assured us that he would come. 3. to state positively or with assurance4. to make (an event) certain; ensure5. (Law) chiefly Brit to insure against loss, esp of life6. (Law) property law another word for convey[C14: from Old French aseürer to assure, from Medieval Latin ass?c?r?re to secure or make sure, from s?c?rus secure] as?surable adj as?surer nCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014as?sure (?????r, ????r) v.t. -sured, -sur?ing. 1. to declare earnestly or confidently to; tell positively: She assured us of our welcome. 2. to cause to know surely; reassure: He assured himself that the alarm was set. 3. to make (a future event) sure; ensure; guarantee. 4. to secure; render safe or stable: to assure a person’s position. 5. to give confidence to; encourage. 6. Chiefly Brit. to insure, as against loss. [1325?75; If you assure someone that something is true or will happen, you tell them that it is definitely true or will definitely happen, often in order to make them less worried.In British English, to ensure that something happens means to make certain that it happens.In American English, this word is usually spelled insure.Insure has another meaning. In both British and American English, if you insure your property, you pay money to a company so that if the property is lost, stolen, or damaged, the company will pay you a sum of money. In this meaning, the spelling is always insure, not ‘ensure’.