1. (a.) Not capable of erring; entirely exempt from liability to mistake\; unerring; inerrable.

2. (a.) Not liable to fail, deceive, or disappoint; indubitable; sure; certain; as, infallible evidence; infallible success; an infallible remedy.

3. (a.) Incapable of error in defining doctrines touching faith or morals. See Infallibility.

absolute acceptable agreeable beyond all praise certain chaste close constant correct defectless delicate dependable direct effective efficacious efficient even exact express faithful faultless fine flawless foolproof handy helpful ideal immaculate impeccable indefectible indefective inerrable inerrant irreproachable just right mathematical micrometrically precise microscopic nice oracular peerless perfect pinpoint precise pure refined reliable religious religiously exact rigid rigorous satisfactory satisfying scientific scientifically exact secure severe sinless spotless square stainless strict subtle sure surefire taintless unadulterated unblemished uncontaminated undeceivable undeviating unerring unfailing unfaultable unmistaken unmixed unspotted untainted useful