Not liable to error:
— An unerring marksman.

synonyms: inerrable, inerrant.

Roget 474: certain, sure, assured etc. v.; solid, well-founded.    unqualified, absolute, positive, determinate, definite, clear, unequivocal, categorical, unmistakable, decisive, decided, ascertained.    inevitable, unavoidable, avoidless^†; ineluctable.    unerring, infallible; unchangeable etc. 150; to be depended on, trustworthy, reliable, bound.    unimpeachable, undeniable, unquestionable; indisputable, incontestable, incontrovertible, indubitable; irrefutable etc. (proven) 478; 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.    sure as fate, sure as death and taxes, sure as a gun.    evident, self-evident, axiomatic; clear, clear as day, clear as the sun at noonday.    ... show more

Roget 946: innocent, not guilty; unguilty^†; guiltless, faultless, sinless, stainless, bloodless, spotless; clear, immaculate; rectus in curia [Lat.]; unspotted, unblemished, unerring; undefiled etc. 939; unhardened^†, Saturnian; Arcadian etc. (artless) 703^†.    inculpable, unculpable^†; unblamed, unblamable^†; blameless, unfallen^†, inerrable^†, above suspicion; irreproachable, irreprovable^†, irreprehensible^†; unexceptionable, unobjectionable, unimpeachable; salvable^†; venial etc. 937.    harmless; inoffensive, innoxious^†, innocuous; dove-like, lamb-like; pure, harmless as doves; innocent as a lamb, innocent as the babe unborn; more sinned against than sinning" [Lear]. virtuous etc. 944; unreproved^†, unimpeached, unreproached^†.    ... show more

Roget 494: real, actual etc. (existing) 1; veritable, true; right, correct; certain etc. 474; substantially true, categorically true, definitively true &c.; true to the letter, true as gospel; unimpeachable; veracious etc. 543; unreconfuted^†, unconfuted^†; unideal^†, unimagined; realistic.    exact, accurate, definite, precise, well-defined, just, just so, so; strict, severe; close etc. (similar) 17; literal; rigid, rigorous; scrupulous etc. (conscientious) 939; religiously exact, punctual, mathematical, scientific; faithful, constant, unerring; curious, particular, nice, delicate, fine; clean-cut, clear-cut.    verified, empirically true, experimentally verified, substantiated, proven (demonstrated) 478.    rigorously true, unquestionably true.    true by definition.    genuine, authentic, legitimate; orthodox etc. 983.1; official, ex officio.    pure, natural, sound, sterling; unsophisticated, unadulterated, unvarnished, unalloyed, uncolored; in its true colors; pukka^†.    well-grounded, well founded; solid, substantial, tangible, valid; undistorted, undisguised; unaffected, unexaggerated, unromantic, unflattering.    ... show more

Polish: nieomylny