The Collaborative International Dictionary of English v.0.48:

Polyuria \Pol`y*u"ri*a\, n. [NL. See Poly-, and Urine.]
   (Med.)
   A persistently excessive flow of watery urine, with low
   specific gravity and without the presence of either protein
   or sugar. It is generally accompanied with more or less
   thirst.
   [1913 Webster]

WordNet (r) 3.0 (2006):

polyuria
    n 1: renal disorder characterized by the production of large
         volumes of pale dilute urine; often associated with
         diabetes