Antonyms for sure

all:

uncertain, unsure.

certain, definite:

doubtful, unconfident, dubious, indefinite, doubted, wavering, unsure, unself-confident, unsteady, humbled, variable, wobbly, swerving, uncertain.

inevitable:

doubting, hesitant.

noun:

disputable, Contradictable, untrusty, avoidable, vacillating, careless, faithless, academic, disputed, answerable, indecisive, improbable, controversial, exploded, apocryphal, groping, treacherous, hypothetical, lying, unassuming, evadable, counterfeit, preventable, perfidious, untrue, disloyal, deceitful, traitorous, negotiable, fictitious, unfaithful, refutable, speculative, diffident, dishonest, fabulous, questionable, unlikely, unauthorized, unsafe, theoretical, baseless, hesitant, inconclusive, recreant, mendacious, fallible, wavering, untruthful, spurious, unconfirmed, untried.

Paraphrases for Sure:

• Adjective :
  'assurance, 'assurer, ,, -absolutely, -certainly, -indeed, able, acceptable, accountable, accuracy, accurate, acknowledged, actual, actually, adequate, AF, affirm, afraid, alert, alleged, anxious, apparent, appropriate, ascertain, ascertained, assumed, assure, attentive, avoid, Avoiding, aware, Aye, bold, build, careful, caring, cautious, ce, certain, certainly, certainty, Checking, clean, clear-cut, collateral, comfortable, committed, concerned, confidence, confident, confirm, confirmed, conscious, considerable, consistent, continued, controlling, convinced, convincing, credible, CURA, curative, daniel, decided, defining, definitive, delighted, dependable, difficult, doubtful, dubious, due, effective, efficient, ensure, ensured, ensures, ensuring, enthusiastic, essential, established, evident, ex-officio, exact, exactly, excess, excessive, explicit, fair, Familiar, fast, few, firm, fixed, forget, fortunate, full, genuine, given, GOTTA, granted, guaranteed, harmless, healthy, heartfelt, here, hopeful, hot, identifiable, identify, identifying, incorrect, inevitable, informed, insecure, inspect, insured, just, keen, kinda, Knew, know, knowing, knowledge, known, life-assurance, likely, limited, little, lucky, maybe, mindful, minimum, mmm-hmm, mode, moderate, mum, natural, necessary, notice, ob, obvious, ok, okey-dokey, optimistic, perfect, plain, please, pleased, positive, precise, precisely, predictable, prescribed, prevent, Preventing, printing, promised, protected, protective, proved, proven, prudent, pure, questionable, quiet, ready, reasonable, related, relative, request, requests, responsible, right, robust, safeguard, safeguarding, safeguards, same, satisfied, say, secure, secured, security, select, selected, self-confident, sensible, serious, several, shall, significant, sincere, slight, so-called, solid, sour, southern, stable, staunch, steady, strong, substantial, successful, such, sufficient, supposed, sure-fire, surethat, sureyou, surprised, sustained, telling, test, then, till, token, trusted, trusting, uh-huh, unaware, uncertain, uncertainty, unclear, unconvinced, undeniable, understand, undetermined, undoubted, unequivocal, unsafe, unsure, Upon, useful, utmost, various, verifying, viable, vigilant, warm, warranty, watertight, well, where, Whether, wholehearted, willing, Without, worried, worrying, wrong, YEP, yes.
• Adverb :
  -but, -if, -lf, absolutely, actually, admittedly, again, Ah, ahead, along, altogether, always, anyway, appropriately, approximately, around, ascertain, awfully, Aye, best, bet, certain, certainly, chemin, Clair, confidently, considerably, damn, definitely, Definitively, determines, determining, doubtless, easily, else, ensure, entirely, especially, evidently, exactly, excessively, fairly, firmly, forget, forward, fully, genuinely, gladly, GOTTA, guys, happily, hardly, here, highly, immediately, indeed, inevitably, issue, just, kindly, know, knows, likely, little, marwan, maybe, mum, naturaily, naturally, necessarily, nevertheless, now, ofcourse, ok, perfect, perfectly, perhaps, plain, please, positively, possibly, precisely, presumably, probably, queer, rather, readily, really, reasonably, relatively, right, roughly, say, secure, shoot, smoothly, some, steadily, successfully, surely, sureyou, swell, terribly, then, thinks, too, understand, understandably, undoubtedly, unquestionably, Upon, virtually, warmly, well, where, willingly, wrong, YEP, yes.
• Interjection :
  -really, -yes, absolutely, Ah, Aye, certainly, exactly, indeed, naturally, Neville, ofcourse, ok, OKAU, please, really, right, understand, well, YEP, yes.
• Noun, singular or mass :
  -yes, assurance, Aye, bet, certainty, confidence, definitely, degree, doubt, EAH, Everything, feller, guarantee, here, measure, mercy, ok, okey-dokey, perfect, period, please, pleasure, positive, ready, right, sake, scratch, secure, sense, series, shoot, uh-huh, well, whatever, where, Whether, YEP, yes.
• Proper noun, singular :
  -yes, absolutely, assure, Aye, certain, certainly, chuckles, definitely, ensure, ensuring, Everything, kids, laughs, ofcourse, ok, probably, really, right, secure, situations, undoubtedly, well, where, Whether, YEP, yes.
• Verb, 3rd person singular present :
  becomes, Does, figures, knows, trusts.
• Verb, non-3rd person singular present :
  're, bet, know, say.
• Verb, past tense :
  Achieved, bet, concerning, exactly, found, Gave, granted, Meant, named, ok, regarding, related, Relating, scared, well, yes.