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The Difference Between “Ensure”, “Insure” and “Assure”

Ensure means "to make something certain to happen". Assure means "to tell someone confidently that something is true". Insure means "to guarantee against loss or harm".

Ensure, assure and insure: a trio of verbs that not only sound similar, but are also closely related in meaning. Let’s see how these words work in English, their correct usage, and more.



“Ensure”, “assure”, and “insure”

MeaningExamples
assure [verb] to say confidently that something is trueWe were assured that everything possible was being done.
ensure [verb] to make certain something will happenThe system ensures equal access to education for all kids.
insure [verb] to guarantee or protect against loss or harmThe car is insured against fire and theft.

Are ensure, assure and insure interchangeable?

  • Ensure means “to make something certain to happen: The company’s sole concern is to ensure the safety of its employees.


  • Assure means “to tell someone confidently that something is true: She assured him that the car would be ready the next day.”


  • Insure means “to guarantee against loss or harm”, or “to provide or obtain insurance”. Example: The house is insured for two million dollars.


To insure is to “guarantee against loss or harm”, or, specifically, “to cover with insurance”. Ensure and insure are frequently confused with each other, since both words have to do with making a guarantee or making certain of something. The difference is that to insure relates more to things of a financial nature, such as insurance. To ensure is more broadly applicable and just means to make sure or certain of something.


Ensure is to “to make sure, certain, or safe”, but without the financial connotation that insure has in protecting against possible loss. This makes the verb ensure more general in application and use, e.g., ‘Please ensure that the doors are locked when you leave‘.

To assure is to tell someone something with confidence so as to reassure or convince them of that thing (usually so that they don’t worry about it). In fact, assure is synonymous with reassure, or words like convince, persuade, and so on. Assure is not quite about making certain something will happen (which is to ensure), but to inspire confidence in another person of something.

“Insure”, used in sentences

Examples: “insure’ used in sentences
He decided to insure his new car against potential accidents and damages.

The business owner knew the importance of insuring the company’s assets to safeguard against unexpected losses.

She wanted to insure her valuable art collection to protect it from theft or damage.

The insurance company offered a policy that would insure the traveler’s belongings during their vacation.

It’s wise to insure your home against natural disasters like floods and earthquakes.

“Ensure”, used in sentences

Examples: “ensure’ shown in sentences
Please ensure that all doors are locked before leaving the building.

The chef took extra care to ensure that each dish was prepared to perfection.

The company implemented strict security measures to ensure the safety of its employees.

Double-check your work to ensure that there are no errors before submitting the report.

The project manager worked tirelessly to ensure that the project was completed on time.

‘Assure’, used in sentences

Examples: “assure’ shown in sentences
She assured her friend that she would be there to support her during the difficult times.

The company’s CEO personally assured the employees that their jobs were secure despite the restructuring.

The doctor assured the patient that the procedure was safe and well-tested.

The teacher assured the students that there would be no pop quizzes that week.

He assured his parents that he would take his studies seriously and improve his grades.



Synonyms of insure/assure/ensure

Synonyms of insure:

  • underwrite
  • guarantee
  • shield
  • cover
  • assure
  • hedge
  • safeguard
  • warranted

Synonyms of ensure:

  • confirm
  • secure
  • guarantee
  • verify
  • check
  • certify
  • corroborate
  • make sure
  • make certain
  • see to it
  • establish
  • set the seal on

Synonyms of assure:

  • reassure
  • convince
  • satisfy
  • persuade
  • guarantee
  • pledge to
  • attest to
  • prove to

Origin of insure

Mid-15c., insuren, spelling variant of ensuren “to assure, give formal assurance” (late 14c.), also “make secure, make safe” (c. 1400).

Origin of ensure

Late 14c., from Anglo-French enseurer, from en- “make” (see en- (1)) + Old French seur “sure” (see sure); probably influenced by Old French asseurer “assure.” Compare insure. Related: Ensured; ensures; ensuring.

Origin of assure

Late 14c., “reassure, give confidence to; make secure or safe, protect; bind by a pledge, give a promise or pledge (to do something),” from Old French asseurer “to reassure, calm, protect, to render sure”, from Latin *assecurar, from ad “to” (see ad-) + securus “safe, secure” (see secure (adj.)). Related: Assured; assuring.

Other commonly confused words

Commonly misused wordsUK English vs. US English
former vs. latterburned or burnt?
bear with vs. bare withcolor or colour?
breathe or breathfavorite vs. favourite
compliment vs. complementsmelled or smelt?
effect vs. affectgray or grey?
elude or alludefavor vs. favour
it’s or itsanalyze or analyse?

Sources  

  1. Harper, Douglas. “Etymology of insure.” Online Etymology Dictionary, https://www.etymonline.com/word/insure. Accessed 13 August, 2023.
  2. Harper, Douglas. “Etymology of ensure.” Online Etymology Dictionary, https://www.etymonline.com/word/ensure. Accessed 13 August, 2023.
  3. Harper, Douglas. “Etymology of assure.” Online Etymology Dictionary, https://www.etymonline.com/word/assure. Accessed 13 August, 2023.

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