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Lavoisier, Antoine Laurent

(Encyclopedia)Lavoisier, Antoine Laurent äNtwänˈ lōräNˈ lävwäzyāˈ [key], 1743–94, French chemist and physicist, a founder of modern chemistry. He studied under eminent men of his day, won early recognit...

zone

(Encyclopedia)zone [Gr.,=girdle], in geography, area with a certain physical and/or cultural unity that distinguishes it from other areas. The division of the earth into five climatic zones probably originated (5th...

Siebold

(Encyclopedia)Siebold tāˈōdōr ĕrnst [key], 1804–85, also a physician, was one of the foremost biologists of his time. He specialized in the comparative anatomy of invertebrates and wrote the first volume (18...

radio frequency

(Encyclopedia)radio frequency, range of electromagnetic waves with a frequency or wavelength suitable for communication uses. Some of these waves serve as carriers of the lower-frequency audio waves; others are mod...

grammar

(Encyclopedia)grammar, description of the structure of a language, consisting of the sounds (see phonology); the meaningful combinations of these sounds into words or parts of words, called morphemes; and the arran...

mental retardation

(Encyclopedia)mental retardation, below average level of intellectual functioning, usually defined by an IQ of below 70 to 75, combined with limitations in the skills necessary for daily living. Daily living skills...

voice, sound produced by living beings

(Encyclopedia)voice, sound produced by living beings. The source of the sound in human speaking and singing is the vibration of the vocal cords, which are inside the larynx, and the production of the sounds is call...

foot, in anatomy

(Encyclopedia)CE5 Foot foot, in anatomy, terminal part of the land vertebrate leg. The term is also applied to any invertebrate appendage used either for locomotion or attachment, e.g., the legs of insects and ...

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 ...

acacia

(Encyclopedia)acacia əkāˈshə [key], any plant of the large leguminous genus Acacia, often thorny shrubs and trees of the family Leguminosae (pulse family). Chiefly of the tropics and subtropics, they are cultiv...