[jee-oid] 
| 1. | an imaginary surface that coincides with mean sea level in the ocean and its extension through the continents. |
| 2. | the geometric figure formed by this surface, an ellipsoid flattened at the poles. |
| ge·oid (jē'oid') n. The hypothetical surface of the earth that coincides everywhere with mean sea level. [German, from Greek geoeidēs, earthlike : gē, earth + -oeidēs, -oid.] ge·oid'al (-oid'l) adj. |
| geoid (jē'oid') Pronunciation Key
The hypothetical surface of the Earth that coincides everywhere with mean sea level and is perpendicular, at every point, to the direction of gravity. The geoid is used as a reference surface for astronomical measurements and for the accurate measurement of elevations on the Earth's surface. |
geoid
model of the figure of the Earth-i.e., of the planet's size and shape-that coincides with mean sea level over the oceans and continues in continental areas as an imaginary sea-level surface defined by spirit level. It serves as a reference surface from which topographic heights and ocean depths are measured. The scientific discipline concerned with the precise figure of the Earth and its determination and significance is known as geodesy.
Learn more about geoid with a free trial on Britannica.com.
ɔɪd
s