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.

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.

Same as Hydrocephaloid.

A water jar; esp., one with a large rounded body, a small neck, and three handles. Some of the most beautiful Greek vases are of this form.

A water nymph.

Pertaining to, or containing, hydrogen; as, hydric oxide.

A compound of the binary type, in which hydrogen is united with some other element.

Having the form or structure of a hydra.

The group of hydroids to which the fresh-water hydras belong.

Same as Hydriodide.

Pertaining to, or derived from, hydrogen and iodine; -- said of an acid (HI) produced by the combination of these elements.

A compound of hydriodic acid with a base; -- distinguished from an iodide, in which only the iodine combines with the base.

A hydro-a/roplane.

Pertaining to, employed in, or produced by, the evolution of electricity by means of a battery in which water or steam is used.

An apparatus for drying anything, as yarn, cloth, sugar, etc., by centrifugal force; a centrifugal.

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

A body formed from bilirubin, identical with urobilin.

A hydro-a/roplane having two supporting planes.

An extensive artificial division of gastropod mollusks, including those that breathe by gills, as contrasted with the Pulmonifera.

Same as Hydrobromide.

Composed of hydrogen and bromine; as, hydrobromic acid.

A compound of hydrobromic acid with a base; -- distinguished from a bromide, in which only the bromine unites with the base.

A compound containing only hydrogen and carbon, as methane, benzene, etc.; also, by extension, any of their derivatives.

Of the nature, or containing, hydrocarbons.

A hydrocarbon. A hydrous carbonate, as malachite.

A white, crystalline, nitrogenous hydrocarbon, C9H9NO, obtained from certain derivatives of cinnamic acid and closely related to quinoline and carbostyril.

Carbureted hydrogen; also, a hydrocarbon.

The hollow stem of a hydroid, either simple or branched. See Illust. of Gymnoblastea and Hydroidea.

A collection of serous fluid in the areolar texture of the scrotum or in the coverings, especially in the serous sac, investing the testicle or the spermatic cord; dropsy of the testicle.

Relating to, or connected with, hydrocephalus, or dropsy of the brain.

Resembling hydrocephalus.

Having hydrocephalus.

An accumulation of liquid within the cavity of the cranium, especially within the ventricles of the brain; dropsy of the brain. It is due usually to tubercular meningitis. When it occurs in infancy, it often enlarges the head enormously.

Same as Hydrochloride.

Pertaining to, or compounded of, chlorine and hydrogen gas; as, hydrochloric acid; chlorhydric.

A compound of hydrochloric acid with a base; -- distinguished from a chloride, where only chlorine unites with the base.

A division of Hydroidea, including those genera that secrete a stony coral, as Millepora and Stylaster. Two forms of zooids in life project from small pores in the coral and resemble those of other hydroids. See Millepora.

See Hydrocyanide.

Pertaining to, or derived from the combination of, hydrogen and cyanogen.

A compound of hydrocyanic acid with a base; -- distinguished from a cyanide, in which only the cyanogen so combines.

Pertaining to, or derived from, the dynamical action of water of a liquid; of or pertaining to water power.

That branch of the science of mechanics which relates to fluids, or, as usually limited, which treats of the laws of motion and action of nonelastic fluids, whether as investigated mathematically, or by observation and experiment; the principles of dynamics, as applied to water and other fluids.

An instrument to measure the velocity of a liquid current by the force of its impact.

Pertaining to, or containing, or obtained from, hydrogen, ferric iron, and cyanogen; as, hydroferricyanic acid. See Ferricyanic.

Pertaining to, or containing, or obtained from, hydrogen, ferrous iron, and cyanogen; as, hydroferrocyanic acid. See Ferrocyanic.

A supposed compound of hydrofluoris acid and a base; a fluoride.

Pertaining to, or containing, hydrogen and fluorine; fluohydric; as, hydrofluoric acid.

A salt of hydrofluosilic acid; a silicofluoride. See Silicofluoride.

Pertaining to, or denoting, a compound consisting of a double fluoride of hydrogen and silicon; silicofluoric. See Silicofluoric.

Pertaining to, produced by, or consisting of, electricity evolved by the action or use of fluids; as, hydrogalvanic currents.

A gaseous element, colorless, tasteless, and odorless, the lightest known substance, being fourteen and a half times lighter than air (hence its use in filling balloons), and over eleven thousand times lighter than water. It is very abundant, being an ingredient of water and of many other substances, especially those of animal or vegetable origin. It may by produced in many ways, but is chiefly obtained by the action of acids (as sulphuric) on metals, as zinc, iron, etc. It is very inflammable, and is an ingredient of coal gas and water gas. It is standard of chemical equivalents or combining weights, and also of valence, being the typical monad. Symbol H. Atomic weight 1.

To hydrogenize.

The act of combining with hydrogen, or the state of being so combined.

A binary compound containing hydrogen; a hydride. [R.] See Hydride.

Hydrogen; -- called also in view of its supposed metallic nature.

To combine with hydrogen; to treat with, or subject to the action of, hydrogen; to reduce; -- contrasted with oxidize.

Of or pertaining to hydrogen; containing hydrogen.

A treatise upon, or a history and description of, the water of the earth.

The negative pole or cathode.

One skilled in the hydrography; one who surveys, or draws maps or charts of, the sea, lakes, or other waters, with the adjacent shores; one who describes the sea or other waters.

The art of measuring and describing the sea, lakes, rivers, and other waters, with their phenomena.

A hydride.

Related to, or resembling, the hydra; of or pertaining to the Hydroidea. One of the Hydroideas.

An extensive order of Hydrozoa or Acaleph/.

Of or pertaining to the motions of fluids, or the forces which produce or affect such motions; -- opposed to hydrostatic.

an enzyme which causes the splitting of a chemical bond with the addition of the elements of water; a hydrolytic enzyme. Formerly called a hydrolytic ferment.

Of or pertaining to hydrology.

One skilled in hydrology.

The science of water, its properties, phenomena, and distribution over the earth's surface.

A chemical process causing the splitting of a chemical bond by the addition of the elements of water. Where the bond which is split is not part of a ring structure, this process causes formation of two compounds from one compound plus water, as in the hydrolysis of the ester bonds of fats during saponification.

Tending to remove or separate water; eliminating water.

A hydrous carbonate of magnesia occurring in white, earthy, amorphous masses.

Divination by means of water, -- practiced by the ancients.

Of or pertaining to divination by water.

That branch of physics which treats of the mechanics of liquids, or of their laws of equilibrium and of motion.

Any medusa or jellyfish which is produced by budding from a hydroid. They are called also Craspedota, and naked-eyed medus/.

A liquor consisting of honey diluted in water, and after fermentation called mead.

See Cyamellone.

Of or pertaining to hydrometallurgy; involving the use of liquid reagents in the treatment or reduction of ores.

The art or process of assaying or reducing ores by means of liquid reagents.

A meteor or atmospheric phenomenon dependent upon the vapor of water; -- in the pl., a general term for the whole aqueous phenomena of the atmosphere, as rain, snow, hail, etc.

Of or pertaining to hydrometeorology, or to rain, clouds, storms, etc.

That branch of meteorology which relates to, or treats of, water in the atmosphere, or its phenomena, as rain, clouds, snow, hail, storms, etc.

An instrument for determining the specific gravities of liquids, and thence the strength spirituous liquors, saline solutions, etc.

Of or pertaining to an hydrometer, or to the determination of the specific gravity of fluids.

An instrument for determining and recording the quantity of water discharged from a pipe, orifice, etc., in a given time.

The art of determining the specific gravity of liquids, and thence the strength of spirituous liquors, saline solutions, etc.

A variety of potash mica containing water. It is less elastic than ordinary muscovite.

An accumulation of urine in the pelvis of the kidney, occasioned by obstruction in the urinary passages.

A hydropathist.

Of or pertaining to hydropathy.

One who practices hydropathy; a water-cure doctor.

The water cure; a mode of treating diseases by the copious and frequent use of pure water, both internally and externally.

Same as Ascites.

A semitranslucent variety of opal that becomes translucent or transparent on immersion in water.

Made transparent by immersion in water.

Any sea snake of the genus Hydrophys and allied genera. These snakes are venomous, live upon fishes, and have a flattened tail for swimming.

A white, crystalline benzene derivative, C8H10O2, obtained by the reduction of phlorone.

An abnormal dread of water, said to be a symptom of canine madness; hence: A viral disease trransmitted by a bite from, or inoculation with the saliva of, a rabid creature, of which the chief symptoms are, a sense of dryness and constriction in the throat, causing difficulty in deglutition, and a marked heightening of reflex excitability, producing convulsions whenever the patient attempts to swallow, or is disturbed in any way, as by the sight or sound of water; rabies; canine madness.

Of or pertaining to hydrophobia; producing or caused by rabies; as, hydrophobic symptoms; the hydrophobic poison.

See Hydrophobia.

The Hydroidea.

An instrument used for the purpose of obtaining specimens of water from any desired depth, as in a river, a lake, or the ocean.

One of the flat, leaflike, protective zooids, covering other zooids of certain Siphonophora.

An aquatic plant; an alga.

The branch of botany which treats of water plants.

Dropsical, or resembling dropsy.

In a hydropical manner.

A species (Polygonum Hydropiper) of knotweed with acrid foliage; water pepper; smartweed.

Of a boat, to move through water while supported by hydroplanes{3} (see hydroplane{3}, above).

Pertaining to, or depending upon, both liquid and gaseous substances; as, hydropneumatic apparatus for collecting gases over water or other liquids.

Same as Dropsy.

A machine for throwing water by hand power, as a garden engine, a fire extinguisher, etc.

A white crystalline substance, C6H4(OH)2, obtained by the reduction of quinone. It is a diacid phenol, resembling, and metameric with, pyrocatechin and resorcin. Called also dihydroxy benzene.

The rootstock or decumbent stem by which a hydroid is attached to other objects. See Illust. under Hydroidea.

A salt supposed to be formed by a hydracid and a base. An acid salt. A hydrous salt; a salt combined with water of hydration or crystallization.

An instrument designed to mark the presence of water, especially in air.

All the zooids of a hydroid colony collectively, including the nutritive and reproductive zooids, and often other kinds.

Pertaining to, or designating, an acid obtained from sorbic acid when this takes up hydrogen; as, hydrosorbic acid.

The aqueous vapor of the entire atmosphere.