prime meridian

prime meridian n. The zero meridian (0°), used as a reference line from which longitude east and west is measured. It passes through Greenwich, England.

prime meridian

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prime meridian

n

(Earth Sciences / Physical Geography) the 0° meridian from which the other meridians or lines of longitude are calculated, usually taken to pass through Greenwich

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prime meridian  (prm)

The meridian with a longitude of 0°, adopted officially in 1884 as a reference line from which longitude east and west are measured and as a basis for standardized time zones. It passes through Greenwich, England, the site of the Royal Greenwich Observatory, which was founded in 1675 and which closed except as a museum in 1998. The prime meridian, together with its opposite meridian having a longitude of 180°, divide the Earth roughly into the Eastern and Western Hemispheres, with those portions of the British Isles, Europe, and Africa that lie west of the prime meridian, considered for practical purposes as belonging to the Eastern Hemisphere. See illustration at time zone.

Thesaurus

Noun

1.

prime meridian - meridian at zero degree longitude from which east and west are reckoned (usually the Greenwich longitude in England) line of longitude, meridian - an imaginary great circle on the surface of the earth passing through the north and south poles at right angles to the equator; "all points on the same meridian have the same longitude"