Ge*od"e*sy (?), n. [Gr. &?;; ge`a, gh^, the earth + &?; to divide: cf. F. géodésie.] (Math.) That branch of applied mathematics which determines, by means of observations and measurements, the figures and areas of large portions of the earth's surface, or the general figure and dimenshions of the earth; or that branch of surveying in which the curvature of the earth is taken into account, as in the surveys of States, or of long lines of coast.

• the geological science of the shape and size of the earth