Spot: What’s the difference between “ensure,” “insure,” and “assure”?

Wednesday, January 22, 2025

What’s the difference between “ensure,” “insure,” and “assure”?

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What's the difference between "ensure," "insure," and "assure"?

Want to understand the difference between "ensure," "insure," and "assure"? While these sound-alike words all deal with protection, knowing their distinct meanings will transform your writing.

Security shield check mark with lock sign

T ry saying "ensure insure assure" as fast as you can five times — you'll likely get tongue tied beyond belief. These three terms all sound quite similar, and to make matters more confusing, they all have definitions along the same lines regarding safety and protection. So how do you determine which of these seemingly indistinguishable words to use? Let's look at the facts and get to the bottom of it.

"Ensure" is a verb with a variety of meanings as defined by the OED. It was first coined during the late 14th century as a verb "to tell (a person) confidently that (something is true)." Other early definitions meant to "pledge one's faith… for the execution of a promise," and "to make (a person) mentally sure." In essence, "ensure" always meant that you were trying to convince someone of a true fact, or a future event that was bound to happen despite their doubts.

"Insure" dates to the mid-15th century. Several of its definitions are quite similar to that of "ensure," according to the Oxford English Dictionary, as it too can mean to "make (a person) sure (of a thing)." But "insure" differs in the context of commerce, as it's also defined as "to secure the payment of a sum of money in the event of loss or of damage." So despite the fact that "ensure" and "insure" sometimes overlap, you would only use "insure" when talking about actual financial support.

Finally we have "assure" — a term that has to do with feeling a sense of safety. People have used "assure" as far back as the late 14th century, and it's defined as "to make safe from or against… risks." It can also mean to "make stable, establish securely." Unlike how "insure" refers to recouping money after a disaster, "assure" is often used in the context of preventing those disasters from ever occurring (again).

So at the end of the day, here's what you need to remember. "Ensure" has to do with the idea of convincing someone of a truth. "Insure" relates to being protected in the wake of a tragic event. "Assure" has to do with establishing a sense of safety to prevent disasters from taking place. Follow those general guidelines and you'll be good to go.