geoid

ge·oid

noun \ˈjē-ˌȯid\

Definition of GEOID

: 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

— ge·oi·dal \jē-ˈȯi-d^əl\ adjective

Origin of GEOID

German, from Greek geoeidēs earthlike, from gē

First Known Use: 1881