Webster's Revised Unabridged Dictionary · 1913

Hygrometric

Hygrometric , adjective

[Compare French hygrométrique.]

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.

Also: Hygrometrical