Sure
Synonyms for sure
adj certain, definite
    confident
    clear
    convinced
    assured
    positive
    abiding
    changeless
    constant
    convincing
    decided
    doubtless
    enduring
    firm
    fixed
    genuine
    incontrovertible
    indisputable
    indubitable
    persuaded
    real
    satisfied
    set
    steadfast
    steady
    telling
    unchangeable
    unchanging
    uncompromising
    undeniable
    unequivocal
    unfailing
    unfaltering
    unqualified
    unquestionable
    unshakable
    unshaken
    unvarying
    unwavering
    valid
    incontestable
    unquestioning
    for a fact
    free from doubt
    never-failing
Antonyms for sure
    uncertain
    unsure
    indefinite
    variable
    unsteady
    wobbly
    doubtful
    dubious
    wavering
    swerving
    doubted
    humbled
    unconfident
    unself-confident
Synonyms
adj physically stable
    safe
    strong
    fast
    firm
    fixed
    secure
    solid
    staunch
    steady
Antonyms
    indefinite
    uncertain
    unsure
    variable
    unsteady
    wobbly
    doubtful
    dubious
    wavering
    swerving
    doubted
    humbled
    unconfident
    unself-confident
Synonyms
adj inevitable
    certain
    assured
    bound
    guaranteed
    indisputable
    ineluctable
    inescapable
    infallible
    irrevocable
    unavoidable
    unerring
    unfailing
    inerrant
    surefire
Antonyms
    doubting
    hesitant
    uncertain
    indefinite
    unsure
    variable
    unsteady
    wobbly
    doubtful
    dubious
    wavering
    swerving
    doubted
    humbled
    unconfident
    unself-confident
Synonyms
adj self-confident
    certain
    decisive
    positive
    assured
    confident
    arrogant
    composed
    decided
    self-assured
self-possessed
Antonyms
    doubting
    hesitant
    uncertain
    unsure
    indefinite
    variable
    unsteady
    wobbly
    doubtful
    dubious
    wavering
    swerving
    doubted
    humbled
    unconfident
    unself-confident
Usage Notes
Both sure and surely are used as intensifying adverbs with the sense “undoubtedly, certainly.” In this use, sure is generally informal and occurs mainly in speech and written representations of speech: She sure dazzled the audience with her acceptance speech. It was sure hot enough in the auditorium. Surely is used in this sense in all varieties of speech and writing, even the most formal: The court ruled that the law was surely meant to apply to both profit-making and nonprofit organizations. See also quick, slow.
Read Also:
- Sure advantage  Synonyms for sure advantage noun hidden advantage reserve trump card decisive argument decisive resource secret advantage secret weapon ace up one’s sleeve card up one’s sleeve 
- Sure as can be  Synonyms for sure as can be adv certainly, without question doubtless precisely unconditionally exactly unquestionably actually definitely surely truly positively really decidedly easily for sure on the nose sure thing conclusively right on categorically come hell or high water decisively no ifs ands or buts no strings attached on the button on the money straight […] 
- Sure as hell  Synonyms for sure as hell adv certainly, without question doubtless precisely unconditionally exactly unquestionably actually definitely surely truly positively really decidedly easily for sure on the nose sure thing conclusively right on categorically come hell or high water decisively no ifs ands or buts no strings attached on the button on the money straight out […] 
- Sure bet  Synonyms for sure bet noun positive assurance confidence trust certitude credence lock sureness surety positiveness steadiness shoo-in stock lockup belief validity firmness cinch faith conviction setup store sure thing inevitability definiteness dogmatism staunchness positivism all sewn up authoritativeness indubitableness open and shut case rain or shine surefire wrap-up Antonyms for sure bet distrust disbelief ambiguity […] 
- Sure bets  Synonyms for sure bets noun positive assurance confidence trust certitude credence lock sureness surety positiveness steadiness shoo-in stock lockup belief validity firmness cinch faith conviction setup store sure thing inevitability definiteness dogmatism staunchness positivism all sewn up authoritativeness indubitableness open and shut case rain or shine sure bet surefire wrap-up Antonyms for sure bets distrust […] 
