[ uh-shoor, uh-shur ]
/ əˈʃʊər, əˈʃɜr /
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See synonyms for: assure / assured / assuring on Thesaurus.com

verb (used with object), as·sured, as·sur·ing.
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Origin of assure

1325–75; Middle English as(e)uren, assuren<Old French aseurer<Late Latin assēcūrāre, equivalent to Latin as-as- + sēcūr- (see secure) + -ā- thematic vowel + -re infinitive suffix


as·sur·er, as·su·ror, nounin·ter·as·sure, verb (used with object), in·ter·as·sured, in·ter·as·sur·ing.pre·as·sure, verb (used with object), pre·as·sured, pre·as·sur·ing.un·as·sur·ing, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What's the difference between assureensure, 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 = reassure
ensure = make sure
insure = cover with insurance

Here’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

Quiz yourself on assure, vs. ensure, vs. insure!

Should assure, ensure, or insure be used in the following sentence?

We need to take action to _____ that this never happens again.

How to use assure in a sentence

British Dictionary definitions for assure

/ (əˈʃʊə) /

verb (tr; may take a clause as object)
to cause to feel sure or certain; convinceto assure a person of one's love
to promise; guaranteehe assured us that he would come
to state positively or with assurance
to make (an event) certain; ensure
mainly British to insure against loss, esp of life
property law another word for convey

Derived forms of assure

assurable, adjectiveassurer, noun

Word Origin for assure

C14: from Old French aseürer to assure, from Medieval Latin assēcūrāre to secure or make sure, from sēcūrus secure
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012