D defs.my
Entry 1 sense Webster, 1913

Hydropneumatic

· Hy·dro·pneu·mat·ic · IPA
01 a. Pertaining to, or depending upon, both liquid and gaseous substances; as, hydropneumatic apparatus for collecting gases over water or other…
  1. 1.
    Pertaining to, or depending upon, both liquid and gaseous substances; as, hydropneumatic apparatus for collecting gases over water or other liquids.