The hypothetical surface of the earth that coincides everywhere with mean sea level.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "geoid" in a sentence
"Let the term geoid apply to the natural irregular surface of the earth and the term spheroid to the ideal regular sur - face of the geodesist which coincides nearly with sealevel and is necessarily a level surface."
"That span can then, in theory, be subtracted from the distance between those satellites and a kind of theoretical sea level known as the geoid, which is what the sea level would be at each point on Earth if undisturbed by weather, tides and currents."
"A new map shows the Earth's "geoid" - the map of its gravitational pull."