Is it ensure, insure, or assure?
late 14c., "persons who dwell on the opposite side of the globe;" 1540s as "place 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" (see foot (n.)); thus, people who live on the opposite side of the world.
Yonde in Ethiopia ben the Antipodes, men that haue theyr fete ayenst our fete. ["De Proprietatibus Rerum Bartholomeus Anglicus," translated by John of Trevisa, 1398]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." Related: Antipodal (adj.); antipodean (1630s, n.; 1650s, adj.).