The Collaborative International Dictionary of English v.0.48:

Viscosimeter \Vis`co*sim"e*ter\, n. [Viscosity + -meter.]
   An instrument for measuring the degree of viscosity of
   liquids, as solutions of gum.
   [1913 Webster]

WordNet (r) 3.0 (2006):

viscosimeter
    n 1: a measuring instrument for measuring viscosity [syn:
         viscometer, viscosimeter]