geoid

noun

ge·​oid ˈjē-ˌȯid 

: 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

jē-ˈȯi-dᵊl 

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

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Word History

Etymology

German, from Greek geoeidēs earthlike, from gē

First Known Use

1881, in the meaning defined above