lon·​gi·​tude | \ ˈlän-jə-ˌtüd How to pronounce longitude (audio) , -ˌtyüd, British also ˈläŋ-gə- \

Definition of longitude

1a : angular distance measured on a great circle of reference from the intersection of the adopted zero meridian with this reference circle to the similar intersection of the meridian passing through the object
b : the arc or portion of the earth's equator intersected between the meridian of a given place and the prime meridian and expressed either in degrees or in time
2 archaic : long duration

Illustration of longitude

Illustration of longitude

longitude 1a: hemisphere marked with meridians of longitude

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Did You Know?

The imaginary (but very important) lines of longitude run from the North Pole to the South Pole. Each is identified by the number of degrees it lies east or west of the so-called prime meridian in Greenwich, England (part of London). A circle is divided into 360°; so, for example, the longitude of the Egyptian city of Cairo is about 31°E—that is, about 31° east of London. The "long" sense of the root may be easier to see in some uses of the adjective longitudinal: A longitudinal study is a research study that follows its subjects over many long years, and a longitudinal engine is one that drives a crankshaft that runs lengthwise under a vehicle (as in rear-wheel-drive cars) rather than crosswise.

Examples of longitude in a Sentence

a map of the world showing lines of latitude and longitude calculating the longitudes of different places The regions are on roughly the same longitude.
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Recent Examples on the Web There is no place on our coast, the longitude of which from Greenwich is so well ascertained as Boston. Scientific American, "Navy Suggests Clocks Be Set to “Boston Mean Time”," 6 Feb. 2020 Below, the cartographic staff built this ingenious rig, with a 40-inch globe representing the moon, to fix the exact position of the thousands of features, with precise latitudes and longitudes. National Geographic, "What are the decade's biggest discoveries?," 25 Dec. 2019 Any debris from Tiangong-2 is expected to fall east of New Zealand, in a region authorities estimate to be within a longitude between 160° to 90° W and latitude between 30° to 45° S—thousands of kilometers from land. Echo Huang, Quartz, "What you need to know about China’s falling space lab Tiangong-2," 18 July 2019 This is in contrast to the longitude and latitude location tracked by several dating apps. Ananya Bhattacharya, Quartz India, "Butterfly wants to give India’s trans community a dating app that puts them first," 7 Jan. 2020 The expert retranslated a primary record of the Grayback’s sinking and found that the longitude differed from a record created in 1946. Fox News, "WWII US submarine wreck discovered 75 years after it sank," 11 Nov. 2019 Cartographers could have anointed any number of imaginary lines to be 0 degrees longitude. Quanta Magazine, "To Test Einstein’s Equations, Poke a Black Hole," 8 Mar. 2018 The space agency produces a detailed set of data using imagery to estimate the world's population by latitude and longitude. Philip Bump, Washington Post, "The breathtaking scale of Santa Claus’s task on Christmas Eve," 20 Dec. 2019 Last year, an amateur researcher in Japan detected a mistake in the latitude and longitude of the spot where the Grayback probably sank. CBS News, "USS Grayback, U.S. submarine missing for 75 years, found off Okinawa, Japan," 11 Nov. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'longitude.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of longitude

15th century, in the meaning defined at sense 1a

History and Etymology for longitude

Middle English, from Latin longitudin-, longitudo, from longus

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Learn More about longitude

Time Traveler for longitude

Time Traveler

The first known use of longitude was in the 15th century

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Statistics for longitude

Last Updated

3 Apr 2020

Cite this Entry

“Longitude.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/longitude. Accessed 7 Apr. 2020.

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More Definitions for longitude


How to pronounce longitude (audio)

English Language Learners Definition of longitude

: distance measured in degrees east or west from an imaginary line (called the prime meridian) that goes from the North Pole to the South Pole and that passes through Greenwich, England
: an imaginary line that circles the Earth at a particular longitude


lon·​gi·​tude | \ ˈlän-jə-ˌtüd How to pronounce longitude (audio) , -ˌtyüd \

Kids Definition of longitude

: distance measured in degrees east or west of an imaginary line that runs from the north pole to the south pole and passes through Greenwich, England

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More from Merriam-Webster on longitude

Rhyming Dictionary: Words that rhyme with longitude

Spanish Central: Translation of longitude

Nglish: Translation of longitude for Spanish Speakers

Britannica.com: Encyclopedia article about longitude

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