What does assure mean?
To assure is to speak with confidence in order to remove another person's doubt or anxiety. When you assure someone, you are making a personal declaration — telling them firmly that a feared outcome will not occur or that a claim is trustworthy, as when a doctor assures a patient that test results are normal. A secondary sense makes assurance a matter of guaranteeing outcomes: careful preparation can assure success, meaning it makes success certain. The word most often appears in interpersonal, reassuring contexts, giving it a warm, calming connotation, though it also carries connotations of authority and certainty. It should not be confused with "ensure" (to make something happen) or "insure" (to cover financially against loss), though all three share the same Latin root meaning "safe." Common collocations include "rest assured" and "I can assure you." Derived forms such as "assurance," "assured," and "reassure" extend the word's reach across everyday speech, business, and diplomacy, making it one of English's essential verbs of confidence.
verbTo tell someone confidently that something is true or will happen, so as to remove doubt or worry.
- To tell someone confidently that something is true or will happen, in order to remove their doubt or anxiety (e.g., 'She assured me the train would arrive on time').
- To make something certain to happen; to guarantee (e.g., 'Careful planning assured the project's success').
- (British English) To insure against loss or damage, especially of life or property.
"The doctor assured her that the results were completely normal."
"The airline assured passengers that their luggage would be on the next flight."
"Years of disciplined saving assured the family a comfortable retirement."
"Rest assured" is such a beloved phrase that it has survived centuries of English — and it's technically redundant, since assuring already means putting someone at ease.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of assure
"Assure" entered English in the late Middle Ages via Old French "asseurer," ultimately deriving from Latin "ad-" plus "securus," meaning "free from care" or "safe." It thus shares its origin with "sure," "secure," "ensure," and "insure," all descendants of the same Latin adjective. Over time the verb settled into its modern core sense of removing doubt by confident statement, with specialized insurance senses developing alongside its French cousins.
Related word forms
How assure is actually used
"Assure" typically takes a person as its object — you assure *someone* of or about something — which distinguishes it from "ensure," which takes a thing or event as its object. The fixed expression "rest assured" means to remain confident that something is true. In insurance contexts, especially British English, "assure" traditionally referred to life assurance while "insure" covered other policies, though this distinction has largely faded.
Easily confused with assure
"Insure" means to arrange financial compensation through an insurance policy, while "assure" means to remove someone's doubts by telling them confidently that something is true.
"Ensure" means to make certain that something happens, whereas "assure" means to convince a person that something is true.