geodesy (n.)

1560s, "the art of land surveying," from Modern Latin geodaesia, from Greek geodaisia "division of the earth;" ultimately from gē "earth" (see Gaia) + stem of daiein "to divide," from PIE *dai-, extended form of root *da- "to divide." In modern use it refers to mathematical calculations derived from measuring large portions of the earth's surface. In this sense, in reference to structures, from 1936.