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.
1. This may sound trivial, but I assure you it is quite important!
2. He hastened to assure me that there was nothing traumatic to report.
3. Mr Brownson, I assure you King's an old enemy of mine.
4. Can you assure me that my father is not suffering?
5. He hastened to assure us that the press would not be informed.