Synonyms of sure

sure 1 of 2

adjective

ˈshu̇r 

1

as in confident

having or showing a mind free from doubt

are you absolutely sure that she said she was coming today?

Synonyms & Similar Words

• confident
• certain
• assured
• positive
• doubtless
• clear
• implicit
• sanguine
• cocksure
• resolute
• decisive
• self-assured
• self-confident
• unhesitating
• unquestioning
• unwavering
• unfaltering
• self-conceited

Antonyms & Near Antonyms

• unsure
• doubtful
• uncertain
• dubious
• hesitant
• indecisive
• unassuming
• wavering
• vacillating
• diffident

2

as in necessary

impossible to avoid or evade

the joke's a sure dud if you don't pause in the right places

Synonyms & Similar Words

• necessary
• inevitable
• possible
• definite
• unavoidable
• certain
• probable
• likely
• inescapable
• destined
• ineluctable
• decided
• in the cards
• in the bag
• unescapable
• ineludible
• settled
• relentless
• fated
• unstoppable
• predetermined
• preordained
• inexorable
• predestined
• unremitting
• foreordained

Antonyms & Near Antonyms

• uncertain
• unsure
• doubtful
• unclear
• avoidable
• questionable
• preventable
• unlikely
• dubious
• shaky
• evadable
• undecided
• unreliable
• unsettled
• improbable
• undependable

3

as in reliable

not likely to fail

a sure cure for the winter blues—a week in the Bahamas

Synonyms & Similar Words

• reliable
• certain
• surefire
• infallible
• fail-safe
• unfailing
• dependable
• can't-miss
• deadly
• unerring

Antonyms & Near Antonyms

• uncertain
• doubtful
• questionable
• fallible

4

as in true

worthy of one's trust

a sister is a sure friend for life

Synonyms & Similar Words

• reliable
• true
• good
• responsible
• safe
• steady
• solid
• dependable
• secure
• loyal
• tried
• trustworthy
• calculable
• trusty
• strong
• faithful
• constant
• devoted
• trustable
• honest
• steadfast
• tried-and-true
• sincere
• fast
• telling
• sound
• staunch
• effective
• confirmed
• valid
• proven
• infallible
• true-blue
• firm
• validated
• unerring
• unquestionable
• verified
• single-minded
• blameless
• attested
• faultless
• guiltless
• authenticated
• impeccable
• irreproachable
• unimpeachable
• inerrant
• bedrock

Antonyms & Near Antonyms

• uncertain
• unsafe
• unreliable
• false
• doubtful
• untrustworthy
• untrue
• treacherous
• uncertain
• suspect
• disloyal
• undependable
• unfaithful
• fickle
• faithless
• lying
• problematic
• questionable
• debatable
• perfidious
• traitorous
• inconstant
• dishonest
• dodgy
• dubious
• deceitful
• hazardous
• mendacious
• fishy
• risky
• shaky
• untruthful
• disputable
• unsound
• shady
• recreant
• unconfirmed
• doubtable
• untried

5

as in conclusive

not capable of being challenged or proved wrong

no sure evidence that life exists on other planets

Synonyms & Similar Words

• conclusive
• positive
• certain
• definite
• undeniable
• indisputable
• unquestionable
• irrefutable
• accomplished
• unanswerable
• indubitable
• incontestable
• unarguable
• incontrovertible
• inarguable
• irrefragable
• unchallengeable
• clear
• unambiguous
• unequivocal
• absolute
• decisive
• undisputed
• unquestioned
• uncontested
• hands-down
• uncontradicted

Antonyms & Near Antonyms

• problematic
• debatable
• questionable
• arguable
• negotiable
• moot
• answerable
• controversial
• doubtful
• disputable
• uncertain
• disputed
• dubious
• ambiguous
• inconclusive
• refutable
• doubtable
• controvertible
• debated
• indecisive
• contradictable
• speculative
• theoretical
• iffy
• hypothetical
• academic
• equivocal

sure

2 of 2

adverb

as in definitely

without any question

we sure could use your help here

Synonyms & Similar Words

• definitely
• certainly
• surely
• clearly
• probably
• really
• likely
• so
• undoubtedly
• truly
• easily
• for certain
• indeed
• assuredly
• damn well
• unquestionably
• doubtless
• undeniably
• indisputably
• possibly
• perhaps
• plainly
• obviously
• alright
• for sure
• by all means
• all right
• inarguably
• incontestably
• unarguably
• incontrovertibly
• by all odds
• hands down
• conceivably
• forsooth
• unmistakably

Synonym Chooser

How does the adjective sure contrast with its synonyms?

Some common synonyms of sure are certain, cocksure, and positive. While all these words mean "having no doubt or uncertainty," sure usually stresses the subjective or intuitive feeling of assurance.

felt sure that I had forgotten something

When is certain a more appropriate choice than sure?

In some situations, the words certain and sure are roughly equivalent. However, 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

When would cocksure be a good substitute for sure?

The words cocksure and sure can be used in similar contexts, but cocksure implies presumptuous or careless positiveness.

you're always so cocksure about everything

Where would positive be a reasonable alternative to sure?

The synonyms positive and sure are sometimes interchangeable, but positive intensifies sureness or certainty and may imply opinionated conviction or forceful expression of it.

I'm positive that's the person I saw

Example Sentences

Recent Examples of sure

Adjective

Brooks Canopy Packable Jacket Brooks is best known for its (literally) record-breaking footwear, sure, but the quality of its apparel line also cannot be overstated. — Stacia Datskovska, Footwear News, 4 Sep. 2026

But scientists weren’t sure if temporary replacement pig organs would cause someone to produce antibodies that could complicate a human-to-human transplant. — O. Rose Broderick, STAT, 4 Sep. 2026

Adverb

For $150 off, the Odyssey G51F sure checks the basic boxes for less. — Kelsey Fogarty, PC Magazine, 24 Aug. 2026

And McCuskey, the primary watchdog over Springfield lawmakers’ offices, sure ran his mouth. — The Editorial Board, Chicago Tribune, 22 Aug. 2026

Phrases Containing sure

• for sure
• sure thing
• to be sure