The Collaborative International Dictionary of English v.0.48:

Astringency \As*trin"gen*cy\ ([a^]s*tr[i^]n"jen*s[y^]), n.
   The quality of being astringent; the power of contracting the
   parts of the body; that quality in medicines or other
   substances which causes contraction of the organic textures;
   as, the astringency of tannin.
   [1913 Webster]

WordNet (r) 3.0 (2006):

astringency
    n 1: a sharp astringent taste; the taste experience when a
         substance causes the mouth to pucker [syn: astringency,
         astringence]
    2: the ability to contract or draw together soft body tissues to
       check blood flow or restrict secretion of fluids [syn:
       astringency, stypsis]