polydipsia

from WordNet (r) 3.0 (2006)

polydipsia
    n 1: excessive thirst (as in cases of diabetes or kidney
         dysfunction)

from The Collaborative International Dictionary of English v.0.48

Polydipsia \Pol`y*dip"si*a\, n. [NL., fr. Gr. poly`s much + ?
   thirst.] (Med.)
   Excessive and constant thirst occasioned by disease.
   [1913 Webster]