The Collaborative International Dictionary of English v.0.48:

Purity \Pu"ri*ty\, n. [OE. purete, purte, OF. purt['e], F.
   puret['e], from L. puritas, fr. purus pure. See Pure.]
   The condition of being pure. Specifically:
   (a) freedom from foreign admixture or deleterious matter; as,
       the purity of water, of wine, of drugs, of metals.
   (b) Cleanness; freedom from foulness or dirt. "The purity of
       a linen vesture." --Holyday.
   (c) Freedom from guilt or the defilement of sin; innocence;
       chastity; as, purity of heart or of life.
   (d) Freedom from any sinister or improper motives or views.
   (e) Freedom from foreign idioms, or from barbarous or
       improper words or phrases; as, purity of style.
       [1913 Webster]

WordNet (r) 3.0 (2006):

purity
    n 1: being undiluted or unmixed with extraneous material [syn:
         purity, pureness] [ant: impureness, impurity]
    2: the state of being unsullied by sin or moral wrong; lacking a
       knowledge of evil [syn: purity, pureness, sinlessness,
       innocence, whiteness]
    3: a woman's virtue or chastity [syn: honor, honour,
       purity, pureness]

Moby Thesaurus II by Grady Ward, 1.0:

230 Moby Thesaurus words for "purity":
   Attic simplicity, Atticism, Christianity, Christlikeness,
   Christliness, Munsell chroma, absoluteness, angelicalness,
   appropriateness, asepsis, assured probity, beauty of holiness,
   blamelessness, blotlessness, brightness, character, chasteness,
   chastity, chroma, chromatic color, chromaticity, clarity,
   classical purity, classicalism, classicism, clean slate,
   cleanliness, cleanly habits, cleanness, clear conscience,
   clearness, color quality, colorimetric quality, combination,
   comeliness, commonness, commonplaceness, cool color, correctness,
   daintiness, decency, decorousness, defectlessness, dignity,
   directness, discrimination, distinction, ease, elegance, elegancy,
   elementarity, erectness, estimableness, fairness, fastidiousness,
   faultlessness, fear of God, felicitousness, felicity, finish,
   fittingness, flawlessness, flow, flowing periods, fluency,
   freshness, fundamentality, fusion, godlikeness, godliness,
   godly-mindedness, good character, good taste, goodness, grace,
   gracefulness, gracility, guilelessness, guiltlessness,
   harmlessness, healthfulness, heavenliness, heavenly-mindedness,
   high ideals, high principles, high-mindedness, holiness,
   holy-mindedness, homeliness, homogeneity, honesty, honor,
   honorableness, hospital cleanliness, hue, identity, immaculacy,
   immaculateness, impeccability, individuality, indivisibility,
   infallibility, innocence, innocency, innocentness, innocuousness,
   intactness, integrality, integration, integrity, inviolability,
   irreducibility, irreproachability, irreproachableness, justice,
   justness, lightness, limpidity, lucidity, matter-of-factness,
   modesty, monism, moral excellence, moral strength, morality,
   naturalness, neatness, neutral color, nobility, nothing to hide,
   odor of sanctity, offenselessness, oneness, ordinariness,
   organic unity, otherworldliness, particularity, pellucidity,
   perfection, perspicuity, plainness, polish, prelapsarian state,
   principles, probity, properness, propriety, prosaicness, prosiness,
   pureness, pureness of heart, rectitude, refinement,
   reproachlessness, reputability, respectability, restraint,
   righteousness, sainthood, saintlikeness, saintliness, saintship,
   salubrity, sanctitude, sanctity, saturation, seemliness,
   selfsameness, seraphicalness, severity, sexual innocence,
   simpleness, simplicity, singleness, singularity, sinlessness,
   smoothness, snowiness, solidarity, solidification, solidity,
   spiritual-mindedness, spirituality, spotlessness, stainlessness,
   starkness, sterility, straightforwardness, taintlessness, taste,
   tastefulness, terseness, tidiness, tint, tone, unadulteration,
   unaffectedness, unblemishedness, unblottedness, uncorruptness,
   undefiledness, undividedness, unearthliness, unguiltiness,
   unification, uniformity, unimpeachability, unimpeachableness,
   uniqueness, unity, univocity, unmixedness, unsoiledness,
   unsophistication, unspottedness, unstainedness, unsulliedness,
   untaintedness, unworldliness, uprightness, upstandingness, value,
   virginity, virtue, virtuousness, warm color, whiteness, wholeness,
   wholesomeness, worthiness