ge·​oid ˈjē-ˌȯid How to pronounce geoid (audio)
: the surface within or around the earth that is everywhere normal to the direction of gravity and coincides with mean sea level in the oceans
geoidal adjective

Example Sentences

Recent Examples on the Web This kind of map - called a geoid - is a standard reference used by topographic maps, and also helps scientists understand how ocean currents flow, how ocean water circulates, and even better understand the dynamics of sea wave heights. Discover Magazine, 7 Dec. 2011 Last month, scientists using the GOCE spacecraft released a model of the Earth's geoid: essentially, a shape telling you which way is down. Phil Plait, Discover Magazine, 21 Apr. 2011 Over time a map of Earth's gravity is built up, resulting in the measurement of the geoid. Phil Plait, Discover Magazine, 31 Mar. 2011 When the geoid is above the ellipsoid, the difference is subtracted. Freddie Wilkinson, National Geographic, 28 Sep. 2020 The vertical distance from a location on the Earth’s surface to mean sea level, as represented by the geoid. Freddie Wilkinson, National Geographic, 28 Sep. 2020 The newest update, however, will use a new mean sea level reference point known as a geoid. Keith Matheny, Detroit Free Press, 2 Mar. 2018 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'geoid.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


German, from Greek geoeidēs earthlike, from

First Known Use

1881, in the meaning defined above

Time Traveler
The first known use of geoid was in 1881

Dictionary Entries Near geoid

Cite this Entry

“Geoid.” Dictionary, Merriam-Webster, Accessed 2 Jun. 2023.

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