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]