assure

Etymology

From Old French asseurer (Modern French assurer), from Latin ad- + securus (“secure”). Cognate with Spanish asegurar. Doublet of assecure.

verb

1. (transitive) To make sure and secure; ensure.
2. (transitive, followed by that or of) To give (someone) confidence in the trustworthiness of (something).
   I assure you that the program will work smoothly when we demonstrate it to the client.
   He assured of his commitment to her happiness.
3. (obsolete) To guarantee, promise (to do something).
4. (transitive) To reassure.