An Etymological Dictionary of Astronomy and Astrophysics

1. The exact or direct opposite.
   

2. Either or both of two points, places, or regions that are situated diametrically opposite to one another on the Earth’s surface (Dictionary.com).

Etymology (EN): M.E., from L., from Gk. antipod-, antipous, literally “with feet opposite,” from → anti- “against,” + pod-, pous, → foot.

Etymology (PE): Pâdpây, from pâd-, → anti-, +
pây, → foot.