Synonyms for For a fact:

• adj.

  •guaranteed (adjective)
  • certified,
  • pledged,
  • confirmed,
  • warranted,
  • sure-fire,
  • have a lock on,
  • on ice,
  • affirmed,
  • sure enough,
  • surefire,
  • endorsed,
  • ascertained,
  • bonded,
  • sealed,
  • approved,
  • secured,
  • attested,
  • assured,
  • protected,
  • insured,
  • Plighted.
  •Other relevant words: (adjective)
  • guaranteed,
  • never-failing,
  • sure,
  • undoubting,
  • free from doubt.
  •sure (adjective)
  • Persuaded,
  • unshakable,
  • unequivocal,
  • convinced,
  • telling,
  • indubitable,
  • unshaken,
  • abiding,
  • confident,
  • unfaltering,
  • decided,
  • satisfied,
  • undeniable,
  • clear,
  • valid,
  • unchanging,
  • firm,
  • unchangeable,
  • convincing,
  • enduring,
  • incontrovertible,
  • unquestionable,
  • set,
  • steady,
  • incontestable,
  • unqualified,
  • unfailing,
  • unvarying,
  • fixed,
  • positive,
  • changeless,
  • indisputable,
  • unwavering,
  • uncompromising,
  • steadfast,
  • constant,
  • unquestioning,
  • genuine.
  •undoubting (adjective)
  • certain.

• adv

  •Other relevant words: (adverb)
  • in spades,
  • terrifically,
  • unmistakably,
  • unequivocally,
  • rigorously,
  • for sure,
  • straight out,
  • in deed,
  • no mistake,
  • precisely,
  • decisively,
  • no strings attached,
  • Veraciously,
  • determinedly,
  • methodically,
  • unerringly,
  • exactly,
  • no catch,
  • on the dot,
  • no ifs ands or buts,
  • in every respect,
  • positively,
  • on the nail,
  • for certain,
  • by all means,
  • faultlessly.
  •precisely (adverb)
  • smack dab,
  • very thing.

• adv.

  •certainly (adverb)
  • cert,
  • unquestionably,
  • posolutely,
  • without fail,
  • of course,
  • right on,
  • assuredly,
  • surely,
  • absolutely.
  •decidedly (adverb)
  • downright,
  • really,
  • strongly,
  • right,
  • flat out,
  • powerful,
  • clearly,
  • real,
  • bloody.
  •exactly (adverb)
  • strictly,
  • bang,
  • sharp,
  • expressly,
  • indeed,
  • truly,
  • altogether,
  • carefully,
  • square,
  • scrupulously,
  • truthfully,
  • completely,
  • definitely,
  • totally,
  • specifically,
  • wholly,
  • utterly,
  • on the nose,
  • faithfully,
  • severely,
  • correctly,
  • literally,
  • just,
  • quite.
  •for sure (adverb)
  • sure thing,
  • no two ways about it,
  • no doubt,
  • dead sure,
  • no question,
  • certainly,
  • for real.
  •Other relevant words: (adverb)
  • terribly,
  • on the money,
  • the ticket,
  • emphatically,
  • no holds barred,
  • explicitly.
  •positively (adverb)
  • flat,
  • without qualification,
  • no kicker,
  • undeniably,
  • really truly,
  • firmly,
  • categorically,
  • amen,
  • easily,
  • to a tee,
  • doubtless,
  • indubitably,
  • with certainty,
  • undoubtedly,
  • Doubtlessly.
  •precisely (adverb)
  • plumb,
  • even,
  • yes,
  • the very thing,
  • accurately,
  • just so,
  • as well,
  • on the button,
  • smack-dab,
  • smack,
  • squarely.

• n.

  •Other relevant words: (noun)
  • decidedly,
  • distinctly.

Antonyms for For a fact:

• adj.

  • guaranteed
    insecure, disapproved, uncertain, unsure.
  • sure
    unsteady, humbled, wobbly, unself-confident, doubtful, swerving, dubious, unconfident, doubted, variable, wavering.

• adv.

  • certainly
    dubiously, doubtfully, equivocally, questionably.
  • exactly
    incompletely, inexactly, indefinite, inaccurately, partially.
  • precisely
    imprecisely.