Source : Webster's Revised Unabridged Dictionary (1913)

Hygrometric \Hy`gro*met"ric\, Hygrometrical \Hy`gro*met"ric*al\,
   a. [Cf. F. hygrom['e]trique.]
   1. Of or pertaining to hygrometry; made with, or according
      to, the hygrometer; as, hygrometric observations.

   2. Readily absorbing and retaining moisture; as, hygrometric
      substances, like potash.