Hydrosulphide noun (Chemistry) One of a series of compounds, derived from hydrogen sulphide by the replacement of half its hydrogen by a base or basic radical; as, potassium hydrosulphide , KSH. The hydrosulphides are analogous to the hydrates and include the mercaptans.

Hydrosulphite noun (Chemistry) A saline compound of hydrosulphurous acid and a base. [ R.]

Hydrosulphuret noun (Chemistry) A hydrosulphide. [ Archaic]

Hydrosulphureted adjective (Chemistry) Combined with hydrogen sulphide.

Hydrosulphuric adjective [ Hydro- , 2 + sulphuric .] (Chemistry) Pertaining to, or derived from, hydrogen and sulphur; as, hydrosulphuric acid, a designation applied to the solution of hydrogen sulphide in water.

Hydrosulphurous adjective (Chemistry) Pertaining to, or designating, an acid obtained by the reduction of sulphurous acid. See Hyposulphurous acid , under Hyposulphurous .

Hydrotellurate noun (Chemistry) A salt formed by the union of hydrotelluric acid and the base.

Hydrotelluric adjective [ Hydro- , 2 + telluric .] (Chemistry) Formed by hydrogen and tellurium; as, hydrotelluric acid, or hydrogen telluride.

Hydrotheca noun ; plural Latin Hydrothecæ , English Hydrothecas . [ New Latin , from English hydra + Greek ... a box.] (Zoology) One of the calicles which, in some Hydroidea (Thecaphora), protect the hydrants. See Illust. of Hydroidea , and Campanularian .

Hydrotherapeutics noun [ Hydro- , 1 + therapeutics .] (Medicine) A system of treating disease by baths and mineral waters.

Hydrotherapy noun [ Hydro- , 1 + therapy .] (Medicine) See Hydropathy .

Hydrothermal adjective [ Hydro- , 1 + thermal .] Of or pertaining to hot water; -- used esp. with reference to the action of heated waters in dissolving, redepositing, and otherwise producing mineral changes within the crust of the globe.

Hydrothorax noun [ Hydro- , 1 + thorax .] (Medicine) An accumulation of serous fluid in the cavity of the chest.

Hydrotic adjective [ Greek "y`dwr water: confer Greek ... moisture, French hydrotique .] Causing a discharge of water or phlegm. -- noun (Medicine) A hydrotic medicine.

Hydrotical adjective Hydrotic.

Hydrotrope noun [ Hydro- , 1 + Greek ... to turn, direct.] A device for raising water by the direct action of steam; a pulsometer.

Hydrotropic adjective [ See Hydrotrope .] (Botany) Turning or bending towards moisture, as roots.

Hydrotropism noun (Botany) A tendency towards moisture.

Hydrous adjective [ Greek "y`dwr water.]
1. Containing water; watery.

2. (Chemistry) Containing water of hydration or crystallization.

Hydroxanthane noun (Chemistry) A persulphocyanate. [ Obsolete]

Hydroxanthic adjective [ Hydro- , 2 + xanthic .] (Chemistry) Persulphocyanic.

Hydroxide noun [ Hydro- , 2 + oxide .] (Chemistry) A hydrate; a substance containing hydrogen and oxygen, made by combining water with an oxide, and yielding water by elimination. The hydroxides are regarded as compounds of hydroxyl, united usually with basic element or radical; as, calcium hydroxide ethyl hydroxide .

Hydroxy- (Chemistry) A combining form, also used adjectively, indicating hydroxyl as an ingredient.

Hydroxy acid (Chemistry) , an organic acid, having (besides the hydroxyl group of the carboxyl radical) an alcoholic hydroxyl group, and thus having the qualities of an alcohol in addition to its acid properties; as, lactic and tartaric acids are hydroxy acids.

Hydroxyl noun [ Hydro- , 2 + ox ygen + -yl .] (Chemistry) A compound radical, or unsaturated group, HO, consisting of one atom of hydrogen and one of oxygen. It is a characteristic part of the hydrates, the alcohols, the oxygen acids, etc.

Hydroxylamine noun [ Hydroxyl + amine .] (Chemistry) A nitrogenous, organic base, NH ₂ .OH, resembling ammonia, and produced by a modified reduction of nitric acid. It is usually obtained as a volatile, unstable solution in water. It acts as a strong reducing agent.

Hydrozoa noun plural [ New Latin , from English hydra + Greek ... an animal.] (Zoology) The Acalephæ; one of the classes of cœlenterates, including the Hydroidea, Discophora, and Siphonophora.

Hydrozoal adjective (Zoology) Of or pertaining to the Hydrozoa.

Hydrozoön noun ; plural Latin Hydrozoa , English Hydrozoöns . [ New Latin ] (Zoology) One of the Hydrozoa.

Hydruret noun [ Hydro- , 2] (Chemistry) A binary compound of hydrogen; a hydride. [ Obsolete]

Hydrus noun [ Latin , a water serpent; also, a certain constellation, Greek "y`dros .] (Astron.) A constellation of the southern hemisphere, near the south pole.

Hye noun & v. See Hie . [ Obsolete] Chaucer.

Hyemal adjective [ Latin hyemalis , or better hiemalis , from hyems , hiems , winter: confer French hyémal .] Belonging to winter; done in winter. Sir T. Browne.

Hyemate intransitive verb [ Latin hiemare , hiematum . See Hyemal .] To pass the winter. [ Obsolete & R.]

Hyemation noun [ Latin hiematio .]
1. The passing of a winter in a particular place; a wintering.

2. The act of affording shelter in winter. [ Obsolete]

Hyen noun [ French hyène .] A hyena. [ Obsolete] Shak.

Hyena noun ; plural Hyenas . [ Latin hyaena , Greek ..., orig., a sow, but usually, a Libyan wild beast, probably , the hyena, from ... hog: confer French hyène . See Sow female hog.] (Zoology) Any carnivorous mammal of the family Hyænidæ , of which three living species are known. They are large and strong, but cowardly. They feed chiefly on carrion, and are nocturnal in their habits. [ Written also hyæna .]

» The striped hyena ( Hyæna striata ) inhabits Southern Asia and a large part of Africa. The brown hyena ( H. brunnea ), and the spotted hyena ( Crocuta maculata ), are found in Southern Africa. The extinct cave hyena ( H. spelæa ) inhabited England and France.

Cave hyena . See under Cave . -- Hyena dog (Zoology) , a South African canine animal ( Lycaon venaticus ), which hunts in packs, chiefly at night. It is smaller than the common wolf, with very large, erect ears, and a bushy tail. Its color is reddish or yellowish brown, blotched with black and white. Called also hunting dog .

Hyetal adjective [ Greek ... rain, from ... to rain.] Of or pertaining to rain; descriptive of the distribution of rain, or of rainy regions.

Hyetograph noun [ Greek ... rain + -graph .] A chart or graphic representation of the average distribution of rain over the surface of the earth.

Hyetographic adjective Of or pertaining to to hyetography.

Hyetography noun The branch of physical science which treats of the geographical distribution of rain.

Hyetology noun [ Greek ... + rain -logy .] The science which treats of the precipitation of rain, snow, etc. -- Hy`e*to*log"ic*al adjective

Hygeia noun [ Latin Hygea , Hygia , from Greek ..., ..., health, ..., Hygeia, from ... sound, healthy.] (Classic Myth.) The goddess of health, daughter of Esculapius.

Hygeian adjective Relating to Hygeia, the goddess of health; of or pertaining to health, or its preservation.

Hygeist noun One skilled in hygiena; a hygienist.

Hygieist noun A hygienist.

Hygiene noun [ French hygiène . See Hygeia .] That department of sanitary science which treats of the preservation of health, esp. of households and communities; a system of principles or rules designated for the promotion of health.

Hygienic adjective [ Confer French hygiénique .] Of or pertaining to health or hygiene; sanitary.

Hygienics noun The science of health; hygiene.

Hygienism noun Hygiene.