prime meridian

[ prahym muh-rid-ee-uhn ]

noun

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

prime meridian

noun

1. the 0° meridian from which the other meridians or lines of longitude are calculated, usually taken to pass through Greenwich

prime meridian

/ 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.

prime meridian

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

Word History and Origins

Origin of prime meridian¹

First recorded in 1860–65

Example Sentences

The route from New York to Istanbul to Santiago would have tacked on two unnecessary crossings of the prime meridian.

From Slate

No one’s contemplating, as Conrad suggested in “The Secret Agent,” blowing up the prime meridian, in the form of the Greenwich Observatory.

From New York Times

Bull Meecham was approaching that prime meridian of inebriation that his wife, his sons, and his daughters, based on a grievously embattled history, had come to fear.

From Literature

The D quadrant covers the longitudes 90 degrees East to zero degrees, the Prime Meridian.

From BBC

“The truth,” Skaife writes, “is that there was no Royal Decree... though there was... a Royal Warrant issued in June 1675, which provided John Flamsteed, who became the first Royal Astronomer, with the funding to set up a proper observatory in Greenwich”—site of the prime meridian, longitude 0 degrees.

From Scientific American