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Persian Wars

(Encyclopedia)Persian Wars, 500 b.c.–449 b.c., series of conflicts fought between Greek states and the Persian Empire. The writings of Herodotus, who was born c.484 b.c., are the great source of knowledge of the ...

psychology

(Encyclopedia)psychology, science or study of the thought processes and behavior of humans and other animals in their interaction with the environment. Psychologists study processes of sense perception, thinking, l...

cholesterol

(Encyclopedia)CE5 cholesterol kəlĕsˈtərōlˌ [key], fatty lipid found in the body tissues and blood plasma of vertebrates; it is only sparingly soluble in water, but much more soluble in some organic solvent...

body temperature

(Encyclopedia)body temperature, internal temperature of a living organism. Mammals and birds are termed warm-blooded, or homeothermic, i.e., they are able to maintain a relatively constant inner body temperature, w...

Tay-Sachs disease

(Encyclopedia)Tay-Sachs disease tāˈ-săksˈ [key], rare hereditary disease caused by a genetic mutation that leaves the body unable to produce an enzyme necessary for fat metabolism in nerve cells, producing cent...

primate

(Encyclopedia)primate, member of the mammalian order Primates, which includes humans, apes, monkeys, and prosimians, or lower primates. The group can be traced to the late Cretaceous period, where members were fore...

psychiatry

(Encyclopedia)psychiatry səkīˈətrē, sī– [key], branch of medicine that concerns the diagnosis and treatment of mental, emotional, and behavioral disorders, including major depression, schizophrenia, and anx...

dinosaur

(Encyclopedia)dinosaur dīˈnəsôr [key] [Gr., = terrible lizard], extinct land reptile of the Mesozoic era. The dinosaurs, which were egg-laying animals, ranged in length from 21⁄2 ft (91 cm) to about 127 f...

turnpike

(Encyclopedia)turnpike, road paid for partly or wholly by fees collected from travelers at tollgates. It derives its name from the hinged bar that prevented passage through such a gate until the toll was paid. See ...

Chordata

(Encyclopedia)CE5 Common features in representative groups of the phylum Chordata Chordata kôrdāˈtə, –däˈ– [key], phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal ...