Defn: Hydraulic.
HYDRAULICON
Hy*drau"li*con, n. Etym: [NL. See Hydraulic.] (Mus.)
Defn: An ancient musical instrument played by the action of water; a water organ. [Written also hydraulis.]
HYDRAULICS
Hy*drau"lics, n. Etym: [Cf. F. hydraulique.]
Defn: That branch of science, or of engineering, which treats of fluids in motion, especially of water, its action in rivers and canals, the works and machinery for conducting or raising it, its use as a prime mover, and the like.
Note: As a science, hydraulics includes hydrodynamics, or the principles of mechanics applicable to the motion of water; as a branch of engineering, it consists in the practical application of the mechanics of fluids to the control and management of water with reference to the wants of man, including canals, waterworks, hydraulic machines, pumps, water wheels, etc. Some writers treat hydraulics and hydrostatics as subdivisions of hydrodynamics.
HYDRAZINE
Hy"dra*zine, n. Etym: [Hydr- + azo- + -ine.] (Chem.)
Defn: Any one of a series of nitrogenous bases, resembling the amines and produced by the reduction of certain nitroso and diazo compounds; as, methyl hydrazine, phenyl hydrazine, etc. They are derivatives of hydrazine proper, H2N.NH2, which is a doubled amido group, recently (1887) isolated as a stable, colorless gas, with a peculiar, irritating odor. As a base it forms distinct salts. Called also diamide, amidogen, (or more properly diamidogen), etc.
HYDRENCEPHSLOID
Hy"dren*ceph"s*loid, a. Etym: [Hydrencephalus + -oid.] (Med.)
Defn: Same as Hydrocephaloid.