Illustration of longitude
- hemisphere marked with meridians of longitude
longitude
noun
lon·gi·tude
ˈlän-jə-ˌtüd 
-ˌtyüd,
British also ˈläŋ-gə-
1
a
: 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
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.
Recent Examples on the Web
The study area covers the high seas of the whole Atlantic Ocean, from 65 degrees South latitude to 65 degrees North latitude and from 90 West longitude to 25 East longitude.
—
Bruce Dorminey, Forbes.com, 23 June 2025
With the quest for longitude over, the observatory explored other avenues of astronomy, such as tracking Earth's magnetic field, viewing planetary transits and characterizing binary star systems.
—Anthony Wood, Space.com, 22 June 2025
Tracking agencies: While the NHC monitors both basins, the Central Pacific Hurricane Center takes over if storms move west past 140°W longitude.
—Brandi D. Addison, Austin American Statesman, 9 June 2025
However, the preliminary report from the CHP contains latitude and longitude coordinates showing the crash occurred on the east side of the overpass, where there is no sidewalk.
—Ariane Lange, Sacbee.com, 17 June 2025
See All Example Sentences for longitude
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Bruce Dorminey, Forbes.com, 23 June 2025
With the quest for longitude over, the observatory explored other avenues of astronomy, such as tracking Earth's magnetic field, viewing planetary transits and characterizing binary star systems.
—Anthony Wood, Space.com, 22 June 2025
Tracking agencies: While the NHC monitors both basins, the Central Pacific Hurricane Center takes over if storms move west past 140°W longitude.
—Brandi D. Addison, Austin American Statesman, 9 June 2025
However, the preliminary report from the CHP contains latitude and longitude coordinates showing the crash occurred on the east side of the overpass, where there is no sidewalk.
—Ariane Lange, Sacbee.com, 17 June 2025
See All Example Sentences for longitude
Cite this Entry
“Longitude.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/longitude. Accessed 21 Jul. 2025.
Copy CitationKids Definition
longitude
noun
lon·gi·tude
ˈlän-jə-ˌt(y)üd
: distance measured by degrees or time east or west from the prime meridian
the longitude of New York is 74 degrees or about five hours west of Greenwich
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