Have you ever written, “We will do everything in our power to insure that your shipment arrives before Friday”? Was this correct? It’s not incorrect, but there’s a better way to use it.
There are three words that confuse people: insure, ensure, and assure.
INSURE means to protect against loss. Example - I’m going to insure the shipment for $5,000.00.
ENSURE means to make sure, make certain, to guarantee. Example - I will ensure that the shipment arrives by Friday.
ASSURE means to give the person confidence, to inform positively. The object of the verb “assure” should always refer to a person. Example - I assure you, we’ll do all possible to get the shipment there by Friday.
Let’s try using all three in one sentence: I assure you, we’ll do all possible to ensure that the insured shipment arrives on time.
INSURE: protect against loss
ENSURE: guarantee, make certain
ASSURE: give confidence