assure

verb

as·​sure ə-ˈshu̇r 

assured; assuring

transitive verb

1

: to make sure or certain : convince

glancing back to assure himself no one was following

2

: to inform positively

I assure you that we can do it.

3

: to make certain the coming or attainment of : guarantee

worked hard to assure accuracy

4

: to make safe (as from risks or against overthrow) : insure

assured the security of the country

5

: to give confidence to

And hereby we know that we are of the truth, and shall assure our hearts …

—1 John 3:19 (King James Version)

Synonyms

• reassure
• comfort
• soothe

Choose the Right Synonym for assure

ensure, insure, assure, secure mean to make a thing or person sure.

ensure, insure, and assure are interchangeable in many contexts where they indicate the making certain or inevitable of an outcome, but ensure may imply a virtual guarantee

the government has ensured the safety of the refugees

, while insure sometimes stresses the taking of necessary measures beforehand

careful planning should insure the success of the party

, and assure distinctively implies the removal of doubt and suspense from a person's mind.

I assure you that no harm will be done

secure implies action taken to guard against attack or loss.

sent reinforcements to secure their position

Examples of assure in a Sentence

I can assure you that you won't be disappointed.

a minister choosing just the right words to assure the grieving parents of the fallen soldier

Recent Examples on the Web

The French club’s Europa League participation next season was assured. —Matt Woosnam, New York Times, 12 July 2025

Police have assured that the scene is a stunt and not a real emergency. —Diana Leyva, The Tennessean, 11 July 2025

Buehrle famously had a couple of beers (or maybe more) in the clubhouse during the game after being assured he wouldn’t be used out of the bullpen, then got the final out in the 14th after Blum’s solo home run gave the Sox the lead in a 7-5 win. —Paul Sullivan, Chicago Tribune, 11 July 2025

Von der Leyen’s victory was all but assured after the parliament’s socialist grouping agreed to back her in exchange for a concession on social spending, but the episode has left her weakened. —semafor.com, 10 July 2025

Word History

Etymology

Middle English, from Anglo-French asseurer, assurer, from Medieval Latin assecurare, from Latin ad- + securus secure

First Known Use

14th century, in the meaning defined at sense 4

Phrases Containing assure

• assure oneself

Rhymes for assure

• abjure
• adjure
• allure
• brochure
• cocksure
• coiffure
• contour
• couture
• demure
• detour
• endure
• ensure

Kids Definition

assure

verb

as·​sure ə-ˈshu̇(ə)r 

assured; assuring

1

: to provide a guarantee of

assure security

2

: to give words of comfort or confidence to : reassure

tried to assure the worried children

3

: to cause to be sure or certain

assure himself that the door was locked

4

: to inform positively

can assure you of her dependability

Legal Definition

assure

transitive verb

as·​sure

assured; assuring

1

chiefly British : insure

2

a

: to inform positively

the seller assured the buyer of his honesty

b

: to provide a guarantee of