Assure, Ensure, and Insure

Commonly Confused Words

assure, ensure, and insure
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The words assure, ensure, and insure are all derived from the Latin word for "secure." Not surprisingly, the meanings of these words overlap.


In a broad sense, the verbs assure, ensure, and insure all mean "to make certain or secure." According to Merriam-Webster's Collegiate Dictionary, "insure sometimes stresses the taking of necessary measures beforehand, and assure distinctively implies the removal of doubt and suspense from a person's mind."

In addition, insure means "to protect against financial loss," and assure, which is almost always used with reference to people, generally means "to promise," "to make sure or safe," or "to inform (someone) in a positive way." In some contexts ensure may imply a virtual guarantee.  

For some finer distinctions (and disagreements), see the usage notes below.


  • "Do not worry about your problems with mathematics. I assure you mine are far greater."
    (attributed to Albert Einstein)

  • "He wondered if she knew in what potential danger she lay; he desired to assure her that he had brought his craft to its nearest perfection and that she had nothing to fear of him."
    (Jean Stafford, "The Interior Castle." The Collected Stories of Jean Stafford. Farrar, Straus and Giroux, 1969/2005)
  • Supervisors should make every effort to ensure the safety of their workers. 
  • A dancer can insure her legs, an opera star her voice, and an actor his distinctive beard. The singer and comedian Jimmy Durante once insured his famous nose through Lloyd's of London.

  • "[T[he documentary evidence was strong enough to convict the embezzler and I sentenced him to a term of from forty to fifty years in prison, thus insuring he would not emerge from the penitentiary to enjoy his ill-gotten gains before he is eighty-three years of age."
    (Bernard Malamud, The Natural. Harcourt, 1952)

    Usage Notes

    • "Use ensure to mean guarantee: Steps were taken to ensure accuracy.

      "Use insure for references to insurance: The policy insures his life.

      "Use assure to mean make sure or give confidence: She assured us the statement was accurate."
      (The Associated Press Stylebook and Briefing on Media Law, 2015)
    • Assure for People, Ensure for Things, and Insure for Money
      "A few commentators . . . suggest assure for people, ensure for things, and insure for money and guarantees (insurance). These are nice distinctions, and you can follow them if you want to. . . .

      "The rest of the recommendation rests on using ensure for general senses and reserving insure for financial senses. This distinction has been urged at least since Fowler 1926, especially by British commentators. It is in general true that insure is used for the financial uses (it must vex the British commentators to find assure still occasionally used in this sense by British technical writers). However, both insure and ensure are used in general senses. . . .

      "Our most recent evidence shows that the distinction between ensure and insure is made more often in British written English than in American written English, and a few commentators hold that insure is more common than ensure in American English."
      (Merriam-Webster's Dictionary of English Usage, 1994)
    • Ensure That . . .
      "A person assures (makes promises to, convinces) other people <our hosts assured us that we would have comfortable rooms>; a person ensures (makes certain) that things occur or that events take place <our hosts ensured that we had comfortable rooms>. To put it a little technically, if the verb is in the active voice, a predicate beginning with that should be introduced by the verb ensure."
      (Bryan A. Garner, Garner's Modern English Usage. Oxford University Press, 2016)
    • Assurance and Insurance
      "European 'life assurance' companies take the position that all policy-holders are mortal and someone will definitely collect, thus assuring heirs of some income. American companies tend to go with 'insurance' for coverage of life as well as of fire, theft, etc."
      (Paul Brians, Common Errors in English Usage. William, James & Co., 2003)


      (a)  We _____ our cars because an accident can easily cost $10,000 or more, especially if it results in a trip to the emergency room.

      (b) "In real life, I _____ you, there is no such thing as algebra."
      (Fran Lebowitz)

      (c) Federal drug regulators need more power and money to _____ the safety of the nation’s drug supply.

      Answers to Practice Exercises

      Glossary of Usage: Index of Commonly Confused Words

      Answers to Practice Exercises: Assure, Ensure, and Insure

      (a) We insure our cars because an accident can easily cost $10,000 or more, especially if it results in a trip to the emergency room.

      (b) "In real life, I assure you, there is no such thing as algebra."
      (Fran Lebowitz)

      (c) Federal drug regulators need more power and money to ensure the safety of the nation’s drug supply.

      Glossary of Usage: Index of Commonly Confused Words

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      Your Citation
      Nordquist, Richard. "Assure, Ensure, and Insure." ThoughtCo, Oct. 26, 2016, Nordquist, Richard. (2016, October 26). Assure, Ensure, and Insure. Retrieved from Nordquist, Richard. "Assure, Ensure, and Insure." ThoughtCo. (accessed March 21, 2018).