sure

1 of 2

adjective

ˈshu̇r 

ˈshər

especially Southern ˈshȯr

surer; surest

1

a

: marked by or given to feelings of confident certainty

I'm sure I'm right

b

: characterized by a lack of wavering or hesitation

sure brush strokes

a sure hand

2

: admitting of no doubt : indisputable

spoke from sure knowledge

3

a

: bound, destined

is sure to win

b

: bound to happen : inevitable

sure disaster

4

: careful to remember, attend to, or find out something

be sure to lock the door

5

: firmly established : steadfast

a sure hold

6

: reliable, trustworthy

a sure friend

7

obsolete : safe from danger or harm

sureness noun

see also:

for sure to be sure

sure

2 of 2

adverb

informal

: surely

Sure vs. Surely: Usage Guide

Sure and surely are both used as simple intensives. Sure is informal and typically used when the speaker or writer expects to be agreed with.

She sure knew how to make me laugh.

That sure was fun.

Surely can occur in formal contexts and is used whether or not agreement is expected.

Surely you jest.

It is often applied when someone is making an effort to persuade.

a book surely worth anyone's time

Synonyms of sure

Adjective

• confident
• certain
• assured
• positive

Adverb

• definitely
• certainly
• surely
• clearly
• probably
• really
• likely

Choose the Right Synonym for sure

sure, certain, positive, cocksure mean having no doubt or uncertainty.

sure usually stresses the subjective or intuitive feeling of assurance.

felt sure that I had forgotten something

certain may apply to a basing of a conclusion or conviction on definite grounds or indubitable evidence.

police are certain about the cause of the fire

positive intensifies sureness or certainty and may imply opinionated conviction or forceful expression of it.

I'm positive that's the person I saw

cocksure implies presumptuous or careless positiveness.

you're always so cocksure about everything

Examples of sure in a Sentence

Adjective

She's not sure who will be there.

Are you sure you want to go?

Are you sure about that?

She'll be there, I'm sure of it.

Are you sure of the results?

The return of the robins is a sure sign of spring.

The letter is a sure indication that she cares.

Pizza is a sure crowd pleaser.

The surest way to lose weight is with diet and exercise.

One sure way to improve your health is to stop smoking.

Adverb

we sure could use your help here

Recent Examples on the Web

Adjective

As a stadium novice, Koy is less sure about how to calibrate his performance. —Todd Longwell, Variety, 18 Mar. 2026

At first, Saunders wasn’t so sure about going all the way to Fargo for college. —Ken Sugiura, AJC.com, 18 Mar. 2026

Adverb

Kate Hudson sure isn't feeling blue today. —Christina Perrier, InStyle, 15 Mar. 2026

Dicky may love ladies, but the Mets sure love Dicky. —Abbey Mastracco, New York Daily News, 14 Mar. 2026

Word History

Etymology

Adjective

Middle English seur, sure, from Anglo-French seur, from Latin securus secure

First Known Use

Adjective

13th century, in the meaning defined at sense 7

Adverb

14th century, in the meaning defined above

Phrases Containing sure

• a good/safe/sure bet
• (as) sure as I'm standing here
• a sure thing
• be sure
• for sure
• good/safe/sure bet
• make sure
• one thing is (for) sure
• sure as hell
• sure bet
• sure-enough
• sure-footed
• sure-handed
• sure of oneself
• sure thing
• to be sure
• yeah, sure

Rhymes for sure

• boor
• cour
• cure
• jure
• lure
• moor
• pure
• spoor
• tour
• abjure
• adjure
• allure

Kids Definition

sure

1 of 2 adjective

ˈshu̇(ə)r 

especially Southern ˈshō(ə)r

1

: firmly established : steadfast

a sure hold

2

: reliable, trustworthy

a sure friend

3

: having no doubt : confident

I'm sure I'm right

4

: not to be doubted : certain

sure evidence

5

a

: bound to happen : inevitable

sure disaster

b

: bound as if by fate

we are sure to win

sureness noun

sure

2 of 2 adverb

1

: surely sense 1b

2

: surely sense 2

Etymology

Adjective

Middle English seur, sure "safe from danger or harm," from early French seur (same meaning), from securus "secure" — related to secure