Source : Webster's Revised Unabridged Dictionary (1913)

Hydrostatics \Hy`dro*stat"ics\, n. [Cf. F. hydrostatique.]
   (Physics)
   The branch of science which relates to the pressure and
   equilibrium of nonelastic fluids, as water, mercury, etc.;
   the principles of statics applied to water and other liquids.

Source : WordNet®

hydrostatics
     n : study of the mechanical properties of fluids that are not in
         motion