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obesity

(Encyclopedia)obesity, condition resulting from excessive storage of fat in the body. Obesity is now usually defined using a formula known as the body mass index (BMI), in which weight (in kilograms) is divided by ...

learning

(Encyclopedia)learning, in psychology, the process by which a relatively lasting change in potential behavior occurs as a result of practice or experience. Learning is distinguished from behavioral changes arising ...

hamster

(Encyclopedia)hamster, Old World rodent, related to the voles, lemmings, and New World mice. There are many hamster species, classified in several genera. All are solitary, burrowing, nocturnal animals, with chunky...

tenrec

(Encyclopedia)tenrec tĕnˈrĕk [key], any of the small insectivorous mammals of the family Tenrecidae, also called tendrecs or tanrecs. These animals are found on the island of Madagascar. In that closed environme...

flea

(Encyclopedia)flea, common name for any of the small, wingless insects of the order Siphonaptera. The adults of both sexes eat only blood and are all external parasites of mammals and birds. Fleas have hard bodies ...

gonadotropic hormone

(Encyclopedia)gonadotropic hormone gōˌnădətrŏpˈĭk [key] or gonadotropin, any one of three glycoprotein (see protein) hormones released by either the anterior pituitary gland or the placenta (the organ in whi...

barium

(Encyclopedia)barium bârˈēəm [key] [Gr.,=heavy], metallic chemical element; symbol Ba; at. no. 56; at. wt. 137.327; m.p. 725℃; b.p. 1,640℃; sp. gr. 3.5 at 20℃; valence +2. Barium is a soft, silver-white, ...

opossum

(Encyclopedia)opossum əpŏsˈəm, pŏsˈ– [key], name for several marsupials, or pouched mammals, of the family Didelphidae, native to Central and South America, with one species extending N to the United States...

hedgehog

(Encyclopedia)hedgehog, Old World insectivorous mammal of the family Erinaceidae. The spiny hedgehogs are found in Africa and Eurasia, except SE Asia. They have rounded bodies up to 13 in. (33 cm) long, very short ...

Aleutian Islands

(Encyclopedia)Aleutian Islands əlo͞oˈshən [key], chain of rugged, volcanic islands curving c.1,200 mi (1,900 km) west from the tip of the Alaska Peninsula and approaching Russia's Komandorski Islands. A partial...

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