assure
UK: əˈʃʊə | US: əˈʃʊr
vt. to tell someone confidently that something is true
vt. to make something certain to happen
vt. (legal) to insure or guarantee formally
The word "assure" entered Middle English from Old French asseurer, which combined the Latin prefix ad- (intensifying action) with securus (free from care). Originally, it meant "to make secure" or "to promise confidently." Over time, it narrowed to emphasize verbal guarantees (e.g., "I assure you") and legal/financial certainty (e.g., "assured insurance"). The core logic ties "directing (as-) toward certainty (sure)."
She assured me the project would be finished on time.
The contract assures delivery within 30 days.
His calm voice assured the nervous passengers.
The certificate assures the authenticity of the product.
Can you assure us that no data was leaked?