Do You Know the Difference Between Insure, Ensure, and Assure?

This month I’m tackling another set of words that sound similar but have different common meanings and usages: ensure, assure, and insure. Do you already know the difference?

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Let’s start with the most straightforward: insure. Just like the word “insurance,” insure means to provide or obtain insurance for. You can think about it as taking precautions before something happens (which is why you get insurance). The most straightforward use is regarding financials.

His board review book collection is so large, he wishes he could insure it for $10,000.

This isn’t the most realistic example, but you get the idea.

Next, let’s review ensure, which means to make certain or sure of something—to guarantee.

The PA student wanted to ensure a passing PANCE score, so she studied hard.

And lastly, assure, which means to positively inform—to give confidence to something. We typically assure people of things.

I assure you I’ll loan you my IM board review flashcards after I’ve taken the exam.

Try out this example:

It is important to insure/ensure/assure the patient does not have a skull fracture or an intracranial hemorrhage.

We’re not discussing financials—we’re not trying to get insurance regarding the patient—so we can strike insure from the possibilities.

So now ensure versus assure. You might be tempted to choose assure because the next two words are “the patient,” and when we assure, we assure people. But in this example, we’re not convincing a patient that they don’t have a fracture. Instead, we’re making sure the patient doesn’t have a skull fracture or intracranial hemorrhage. We want to be certain or sure of something, which means ensure is the correct word here. 

It is important to ensure the patient does not have a skull fracture or an intracranial hemorrhage.

Try out this example from fellow copyeditor Melinda:

The doctor needs to insure/ensure healing to ensure/assure the patient they’ll be fine.

Here’s the correct sentence:

The doctor needs to ensure healing to assure the patient they’ll be fine.

How did you do? In this example, the doctor needs to be sure (ensure) that healing is progressing in order to confidently tell (assure) the patient they’ll be fine.

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So there you have it: three similar-sounding words with three different meanings. I assure you it’s possible to get them straight!