2. (Chem.)

Defn: A combining form of hydrogen, indicating hydrogen as an ingredient, as hydrochloric; or a reduction product obtained by hydrogen, as hydroquinone.

HYDRO-AEROPLANE
Hy"dro-a"ër*o*plane`. (Aëronautics)

Defn: An aëroplane with a boatlike or other understructure that enables it to travel on, or to rise from the surface of, a body of water by its own motive power.

HYDROBAROMETER
Hy`dro*ba*rom"e*ter, n. Etym: [Hydro-, 1 + barometer.]

Defn: An instrument for determining the depth of the sea water by its pressure.

HYDROBILIRUBIN
Hy`dro*bil`i*ru"bin, n. Etym: [Hydro-, 2 + bilirubin.] (Physiol.
Chem.)

Defn: A body formed from bilirubin, identical with urobilin.

HYDROBIPLANE
Hy"dro*bi"plane, n.

Defn: A hydro-aëroplane having two supporting planes.