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hyacinth, in botany

(Encyclopedia)hyacinth, any plant of the genus Hyacinthus, bulbous herbs of the family Liliaceae (lily family) native to the Mediterranean region and South Africa. The common, or Dutch, hyacinth of house and garden...

Hyades, in astronomy

(Encyclopedia)Hyades hīˈədēz [key], in astronomy, open star cluster in the constellation Taurus, located immediately to the right of the bright star Aldebaran. The cluster is about 130 light-years from the eart...

hydra, in zoology

(Encyclopedia)hydra hīˈdrə [key], common name for freshwater organisms in the phylum Cnidaria, which includes jellyfish, sea anemones, and corals. Hydras are widely distributed in lakes, ponds, and sluggish stre...

Hydra, in astronomy

(Encyclopedia)Hydra, in astronomy, southern constellation lying S of Corvus, Crater, Virgo, Leo, and Cancer. It is a long, slender, winding constellation traditionally depicted as a snake and known also as the Wate...

antipodes, in geography

(Encyclopedia)antipodes [Gr.,=having feet opposite], people or places diametrically opposite on the globe. Thus antipodes must be separated by half the circumference of the earth (180°), and one must be as far nor...

Islam in Africa

(Encyclopedia)Islam in Africa, the development of the Muslim religion on the African continent. During Muhammad's lifetime a group of Muslims escaped Meccan persecution (615) by fleeing to Ethiopia, where the Negus...

apostrophe, in punctuation

(Encyclopedia)apostrophe: see punctuation; abbreviation. ...

Io, in astronomy

(Encyclopedia)Io īˈō [key], in astronomy, one of the 39 known moons, or natural satellites, of Jupiter. Io is subject to Jupiter's enormous tidal forces and is, as a result, the most volcanically active body in ...

ion, in chemistry

(Encyclopedia)ion, atom or group of atoms having a net electric charge. Ionization has many applications. Vapor lamps and fluorescent lamps take advantage of the light given off when positive ions recombine with ...

iris, in anatomy

(Encyclopedia)iris: see eye.