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growth hormone

(Encyclopedia)growth hormone or somatotropin sōmătˌətrōˈpən [key], glycoprotein hormone released by the anterior pituitary gland that is necessary for normal skeletal growth in humans (see protein). Evidence...

aster

(Encyclopedia)CE5 Cross section of a sunflower, a member of the aster family aster [Gr.,=star], common name for the Asteraceae (Compositae), the aster family, in North America, name for plants of the genus Aste...

Celt

(Encyclopedia)Celt kĕlt [key]. 1 One who speaks a Celtic language or who derives ancestry from an area where a Celtic language was spoken; i.e., one from Ireland, the Scottish Hebrides and Highlands, the Isle of M...

zebra

(Encyclopedia)zebra, herbivorous hoofed African mammal of the genus Equus, which also includes the horse and the ass. It is distinguished by its striking pattern of black or dark brown stripes alternating with whit...

Houston, Samuel

(Encyclopedia)Houston, Samuel, 1793–1863, American frontier hero and statesman of Texas, b. near Lexington, Va. In 1836 Houston was elected the first president of the new Republic of Texas. The independence of ...

kangaroo

(Encyclopedia)kangaroo, name for a variety of hopping marsupials, or pouched mammals, of the family Macropodidae, found in Australia, Tasmania, and New Guinea. The term is applied especially to the large kangaroos ...

Ur

(Encyclopedia)Ur ûr [key], ancient city of Sumer, S Mesopotamia. The city is also known as Ur of the Chaldees. It was an important center of Sumerian culture (see Sumer) and is identified in the Bible as the home ...

tunicate

(Encyclopedia)tunicate to͞oˈnəkĭt [key], marine animal of the phylum Chordata, which also includes the vertebrates. The adult form of most tunicates (also called urochordates) shows no resemblance to vertebrate...

tower

(Encyclopedia)tower, structure, the greatest dimension of which is its height. Towers have belonged to two general types. The first embodies practical uses such as defense (characteristic of the Middle Ages), to ca...

sequoia

(Encyclopedia)sequoia sĭkwoiˈə [key], name for the redwood (Sequoia sempervirens) and for the big tree, or giant sequoia (Sequoiadendron giganteum), both huge, coniferous evergreen trees of the bald cypress fami...