The Collaborative International Dictionary of English v.0.48:

Faultless \Fault"less\, a.
   Without fault; not defective or imperfect; free from blemish;
   free from incorrectness, vice, or offense; perfect; as, a
   faultless poem.
   [1913 Webster]

         Whoever thinks a faultless piece to see,
         Thinks what ne'er was, nor is, nor e'er shall be.
                                                  --Pope.

   Syn: Blameless; spotless; perfect. See Blameless. --
        Fault"less*ly, adv.-Fault"less*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

faultless
    adj 1: without fault or error; "faultless logic"; "speaks
           impeccable French"; "timing and technique were
           immaculate"; "an immaculate record" [syn: faultless,
           immaculate, impeccable]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "faultless":
   OK, absolute, accurate, all right, angelic, beyond all praise,
   blameless, chaste, childlike, clean, clear, correct, dead right,
   defectless, dovelike, entire, errorless, exemplary, exquisite,
   flawless, foolproof, guiltless, ideal, immaculate, impeccable,
   in the clear, incorrupt, inculpable, indefectible, indefective,
   infallible, innocent, intact, irreproachable, just, just right,
   lamblike, letter-perfect, meticulous, not guilty, offenseless,
   okay, peerless, perfect, prelapsarian, pristine, proper, pure,
   reproachless, right, sans reproche, sinless, spotless, stainless,
   straight, straight-up-and-down, taintless, unadulterated,
   unblemished, uncontaminated, uncorrupted, undefiled, unfallen,
   unfaultable, unimpeachable, unlapsed, unmixed, unspotted,
   untainted, untouched by evil, whole, with clean hands,
   without reproach