Assure, ensure, insure, and one mean old shark

Lesson: When to use assure, ensure, and insure

Last week I was waiting in my doctor’s office, casually taking in the wall art (you know, the cartoon man coughing phlegm into a face mask to remind you to be careful where you spew your germs and the step-by-step instructions on how not to freak out your kids when they get their shots . . .) when I came across a truly frightening memorandum. It read: To assure we stay on schedule, please arrive 15 minutes before your appointment.

I took deep breaths and convinced myself not to bring up this incorrect word choice to the doctor, figuring I didn’t need “crazy grammar freak” written in my medical records. But later, when the doctor was discussing putting me on a new heart medicine, I did start to get nervous. If she didn’t notice that assure should have been ensure, what if she made another mistake, like instead of writing me a prescription to help my heart, she gave me something that would liquefy my liver. (Though, perhaps if I had less paranoia, these heart palpitations would go away on their own.)

The point is: Many English words sound similar, and it can be tricky to figure out what word to use when. As we continue our language adventures on this blog, I will help demystify word choice for you. This is important because, as you can tell from my anecdote, using the wrong word can change a person’s perception of you, and this doesn’t just pertain to persnickety wordsmiths.

Today we’re going to look at assure, ensure, and insure.


Assure means to encourage or promise someone that a certain outcome will happen.

Example: I assure you, if you wear your shark-repellant mask, no shark will eat your face off.

Ensure is something you do to guarantee an outcome.

Example: Wearing your shark-repellant mask will ensure no shark will eat your face off.

Insure involves financial liability, such as with health or life insurance.

Example: You should insure your face in case a shark eats it off.

What other words bring you confusion? Feel free to comment on this post and let me know what topics I should write about in the future.

5 thoughts on “Assure, ensure, insure, and one mean old shark

  1. I had a boss once who told me the words ensure and insure were totally interchangeable. I’m so glad you clarified this matter to MY satisfaction. 🙂 I’ll probably never see him again, and I’m not so sure I’d want to.


    • Last year I edited a 600-page book detailing how to improve the public education system. I don’t know how many times I changed “assure” to “ensure” in the manuscript. It really undermined the author’s message.


  2. I would like to assure you that I like you and this post. To ensure you receive the message, I will repeat: I like you and this post. I’m so glad that I don’t have to encounter the words on how and why people are insured.


  3. Done. I think I can’t help but become a follower of this blog!

    I love the topic of this post because incorrect word choice is one of those things that makes me twitch. If you feel the same, please take a moment to suffer through this email that was sent to me from my boss:
    (in regard to setting up a meeting time)
    “Allie July 15th date is perfect. I think that would be suffusion. Thank you, (name omitted to protect remaining shreds of dignity)”

    My guess is that “sufficient” was intended… LOL/fml


  4. Finely i fount out the best definition of insure and ensure. It is almost six month i have been learning English language and i need more info about hidden tips and tricks of that language. Also click here and find out more information about that if you need. There are also great examples of insure and ensure definition.


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