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prime meridian

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noun

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

Origin of prime meridian

First recorded in 1860–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for prime meridian

prime meridian

noun

the 0° meridian from which the other meridians or lines of longitude are calculated, usually taken to pass through Greenwich
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
prime meridian in Science

prime meridian

[prīm]

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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
prime meridian in Culture

prime meridian

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

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.