antipodes (n.)

late 14c., "persons who dwell on the opposite side of the globe;" from 1540s as "country or region on the opposite side of the earth," from Latin antipodes "those who dwell on the opposite side of the earth," from Greek antipodes, plural of antipous "with feet opposite (ours)," from anti "opposite" (see anti-) + pous "foot" (from PIE root *ped- "foot").

Yonde in Ethiopia ben the Antipodes, men that haue theyr fete ayenst our fete. [Bartholomew Glanville, "De proprietatibus rerum," c. 1240, translated by John of Trevisa c. 1398]

Belief in them could be counted as a heresy in medieval Europe, when the orthodox supposition was that the whole of the earth was a flat surface. Not to be confused with antiscii "those who live on the same meridian on opposite side of the equator," whose shadows fall at noon in the opposite direction, from Greek anti- + skia "shadow." Also see antoecian. Related: Antipodist.