certainty; necessity; certitude, surety, assurance; dead certainty, moral certainty; infallibleness; infallibility, reliability; indubitableness, inevitableness, unquestionableness., gospel, scripture, church, pope, court of final appeal; res judicata, ultimatum positiveness; dogmatism, dogmatist, dogmatizer; doctrinaire, bigot, opinionist, Sir Oracle; ipse dixit., fact; positive fact, matter of fact; fait accompli.

be certain; stand to reason., render certain; insure, ensure, assure; clinch, make sure; determine, decide, set at rest, "make assurance double sure" [Macbeth]; know (believe)., dogmatize, lay down the law.

certain, sure, assured; solid, well-founded., unqualified, absolute, positive, determinate, definite, clear, unequivocal, categorical, unmistakable, decisive, decided, ascertained., inevitable, unavoidable, avoidless; ineluctable., unerring, infallible; unchangeable; to be depended on, trustworthy, reliable, bound., unimpeachable, undeniable, unquestionable; indisputable, incontestable, incontrovertible, indubitable; irrefutable (proven); conclusive, without power of appeal., indubious; without doubt, beyond a doubt, without a shade or shadow of doubt, without question, beyond question; past dispute; clear as day; beyond all question, beyond all dispute; undoubted, uncontested, unquestioned, undisputed; questionless, doubtless., authoritative, authentic, official.

certainly; for certain, certes, sure, no doubt, doubtless, and no mistake, flagrante delicto, sure enough, to be sure, of course, as a matter of course , a coup sur, to a certainty; in truth (truly); at any rate, at all events; without fail; coute que coute, coute qu'il coute; whatever may happen, if the worst come to the worst; come what may, happen what may, come what will; sink or swim; rain or shine.