Definify.com

Webster 1913 Edition

Adj.

[

Hydro-

, 1 +

pneumatic

: cf. F.

hydropneumatique

Pertaining to, or depending upon, both liquid and gaseous substances;

as,

hydropneumatic

apparatus for collecting gases over water or other liquids

Adj.

[Gr. water, and inflated, breath, spirit.]

An epithet given to a vessel of water, with other apparatus for chimical experiments.

hydropneumatic ‎(not comparable)

Operated by both fluid and air power
Being, or pertaining to, a type of automotive suspension system based on a nitrogen springing medium.