prime meridian

American  

[prahym muh-rid-ee-uhn] / ˈpraɪm məˈrɪd i ən /

noun

1. the prime meridian, the meridian running through Greenwich, England, from which longitude east and west is reckoned.

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prime meridian British  

noun

1. 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 Scientific  

/ prīm /

1. 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.

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prime meridian Cultural  

1. The meridian at zero degrees longitude. All longitude is measured relative to the prime meridian, which passes through Greenwich, England.

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Etymology

Origin of prime meridian

First recorded in 1860–65