Meaning of geoid

ge•oid

Pronunciation: ( jē'oid), [key]
— n.
  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.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.