The Collaborative International Dictionary of English v.0.48:

Flawless \Flaw"less\, a.
   Free from flaws. --Boyle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

flawless
    adj 1: without a flaw; "a flawless gemstone" [syn: flawless,
           unflawed]

Moby Thesaurus II by Grady Ward, 1.0:

66 Moby Thesaurus words for "flawless":
   OK, absolute, accurate, all right, beyond all praise, chaste,
   clean, correct, dead right, defectless, demonstrable, entire,
   errorless, exquisite, faultless, foolproof, ideal, immaculate,
   impeccable, indefectible, indefective, infallible, intact,
   irrefutable, irreproachable, just, just right, letter-perfect,
   meticulous, model, okay, peerless, perfect, pristine, proper, pure,
   right, sinless, sound, spotless, stainless, straight,
   straight-up-and-down, taintless, unadulterated, unassailable,
   unblemished, unbroken, uncontaminated, uncorrupted, undamaged,
   undeniable, unfaultable, unflawed, unimpaired, unimpeachable,
   unmarred, unmixed, unquestionable, unsoiled, unspotted, unsullied,
   untainted, untarnished, virgin, whole