assure
Americanverb (used with object)
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to declare earnestly to; inform or tell positively; state with confidence to.
She assured us that everything would turn out all right.
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to cause to know surely; reassure.
He assured himself that no one was left on the bus.
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to pledge or promise; give surety of; guarantee.
He was assured a job in the spring.
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to make (a future event) sure; ensure.
This contract assures the company's profit this month.
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to secure or confirm; render safe or stable.
to assure a person's position.
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to give confidence to; encourage.
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Chiefly British. to insure, as against loss.
verb
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to cause to feel sure or certain; convince
to assure a person of one's love
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to promise; guarantee
he assured us that he would come
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to state positively or with assurance
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to make (an event) certain; ensure
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to insure against loss, esp of life
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property law another word for convey
Usage
What's the difference between assure, ensure, and insure? Assure usually means to tell someone something with confidence or to cause someone to know something with certainty—it often means the same thing as reassure. Ensure most commonly means to guarantee or make certain, as in Working hard ensures success. Insure typically means to guarantee against loss or harm or, more specifically, to cover with insurance. It’s no wonder there’s confusion between the three words—all three are verbs that are based on the Latin root sēcūrus, meaning safe. Making things even more confusing is the fact that ensure and insure can be used interchangeably in most senses. Still, insure is much more commonly used in the context of insurance, like car insurance, health insurance, and homeowner’s insurance. These kinds of insurance insure you—they give you coverage that provides you with compensation in certain cases and situations. Ensure is typically used in a more general way in the context of actions that are done to make sure that something happens or is the case, as in We need to ensure that the meeting starts on time. Assure is always used in the context of communication, especially in situations in which someone is trying to make someone else feel better about something. It’s used in the phrase rest assured. Here’s a quick cheat sheet to remember the most common uses of each word:assure = reassureensure = make sureinsure = cover with insuranceHere’s an example of assure, ensure, and insure used correctly in a sentence. Example: She assured me that the company has ensured that every employee has the opportunity to be insured. Want to learn more? Read the full breakdown of the difference between assure, ensure, and insure.
Other Word Forms
Etymology
Origin of assure
First recorded in 1325–75; Middle English as(e)uren, assuren, from Old French aseurer, from Late Latin assēcūrāre, from Latin as- as- + sēcūr(us) ( see secure) + -āre, infinitive suffix
Explanation
If you assure your boss that you’ll finish your project by Tuesday, you are making a promise or commitment to have it done by Tuesday. The verbs insure and ensure look and sound like assure but they aren't synonyms. There is some overlap in meaning — all of them can mean “to make secure or certain” — but assure is generally used in situations when you are referring to a person: “I assure you that I haven’t forgotten about driving you to the airport,” or “He called his mother to assure her that everything will be fine.”
Vocabulary lists containing assure
"To Kill a Mockingbird" by Harper Lee, Chapters 7–11
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List 4
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Bridge to Terabithia
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
“We want to assure the community that the protection and welfare of animals in our city remains a high priority,” police wrote in the release.
From Los Angeles Times • May 14, 2026
“I can assure you, this is just the start about what’s to come in Mexico,” Cole said.
From The Wall Street Journal • May 14, 2026
"They assure me that everything I have is treatable," she said.
From Barron's • May 4, 2026
After his talks, Magyar sought to assure Hungarians that the EU did not support conditions that would be contrary to their country's interests.
From BBC • Apr. 29, 2026
“I assure you, Mr. Harley-Dickinson, your zoo story was nothing short of riveting, and I would hear it again in a heartbeat. But the children have a somewhat unusual background,” she said cautiously.
From "The Hidden Gallery" by Maryrose Wood
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
