Ensure vs. Insure vs. Assure: Is There a Difference?

If you’ve ever wondered what the difference is between ensure and insure, you’re definitely not alone. And to make things even more confusing, we can also throw in assure, which has a similar sound and meaning. WHY do we need all three of these words, and are their meanings actually that different?

According to Merriam-Webster, these three words—insure, ensure, and assure—DO have distinct, individual meanings; however, some of their definitions also overlap with one or even both of the others. Let’s dive in to clear up the confusion.

The Overlap

We’ll start with what these words have in common. Truth be told, that’s a lot.

All you need to do to see that these words are incredibly similar is grab a thesaurus. When I looked up the synonyms of each word on Merriam-Webster’s online dictionary, I found my confirmation.

Both assure and ensure appeared as synonyms for insure.

The same happened for ensure: both assure and insure were listed as synonyms.

However, neither insure nor ensure made the short list of synonyms for assure, which I thought was very interesting! We’ll get to that more when we discuss these words’ differences.

If you had to create one definition that could apply to all three words, it would probably be “to make sure, certain, or safe.” There are little caveats and differences in how each word expresses this, but that general definition could be applied to any of the three.

With that commonality as the basis, let’s talk about the differences.

How Are They Different?

First, let’s bring up the dictionary definition of each word.

Definitions

Ensure: to make sure, certain, or safe; guarantee

Insure: to provide or obtain insurance on or for; to make certain especially by taking necessary measures and precautions

Assure: to make sure or certain; convince or give confidence to; to inform positively; guarantee; to make safe (as from risks or against overthrow)

Although the words are almost interchangeable in some contexts, they have their differences.

Insure is usually reserved for financial contexts. When you’re talking about literal insurance (like health insurance, home insurance, etc.), you cannot use ensure or assure—only insure will do. This word has the connotation of assigning a specific monetary value to an item.

Ensure is usually used in more general contexts. Ensure carries a more causal meaning of “making certain.” In many cases, you could replace ensure with make sure and you would not lose any meaning. Take this for example: “She ensured the entire collection was accounted for before leaving the store.” We could replace ensured with made sure and it would still make sense: “She made sure the entire collection was accounted for before leaving the store.”

Assure is usually used specifically for people. When you’re assuring, you’re usually assuring SOMEONE. You’re trying to remove doubt from a person’s mind. The only time you can INSURE a person is with a life insurance policy, and you cannot ENSURE a person at all. However, you can definitely ASSURE a person, as in this example: “My mom was worried about my move, but I assured her that I would be careful.”

In short, use insure in the financial sense of taking monetary precautions, ensure in the general sense of securing a specific outcome, and assure for removing doubt from a person’s mind.

Put another way, we insure houses, valuable items, cars, etc. We ensure control, a specific outcome, and accountability. We assure a person by removing doubt from their mind.

The Chicken or the Egg

Have these words always been distinct? Which one came first?

The dictionary states that assure was first, originating in the 14th century. Insure came next, with its first known use in 1635. Ensure came last, popping up around the 1740s.

For hundreds of years, ensure and insure were simply variant spellings of the same word. It was like canceled and cancelled—they meant the same thing, but people just spelled them different ways.

Then, around the middle of the 1800s (which, you might have noticed from other posts, is when grammarians really started to get picky about the English language), people decided they wanted to crack down on the two words and assign them distinct meanings. That’s when they decided on “insure = finances; ensure = general outcomes; assure = people.”

Examples

My boss assured me that he would ensure my new, salaried position included health insurance.

Ensure

To ensure the safety of the passengers, airlines must provide detailed evacuation instructions.

The grocer recommended I store the meat in the freezer to ensure it wouldn’t go bad before I needed it.

If you want to ensure your day is off to a great start, drink water right when you wake up.

Our apartment complex recommended leaving faucets on drip to ensure the pipes don’t freeze.

Insure

You should always insure your house against fire and water damage.

It was cheaper to insure our car with State Farm than with Progressive.

According to Sports Illustrated, David Beckham insured his legs for £100 million, which was a record in 2006.

Assure

I can assure you that you aren’t the only one who has been confused by these three words.

The gamble was risky, but Frank assured Jim that it would pay off.

If you have home insurance, you can rest assured that your assets are protected.

Do you have any more questions about ensure, insure, and assure? If so, drop them in the comments and I’ll find an answer for you!

Click here to learn the difference between that and which!

Sources:

• “America’s Most Trusted Dictionary.” Merriam-Webster. Accessed August 7, 2024. https://www.merriam-webster.com/.
• Merriam-Webster. Merriam-Webster’s Dictionary of English Usage. 14th ed. Taunton, MA: QuadGraphics, 2016.