an·tip·o·dal
/anˈtipǝd(ǝ)l/
adjective
1. relating to or situated on the opposite side of the earth.
diametrically opposed to.
2. In astronomy, "antipodal" describes celestial objects or points that are diametrically opposite each other on the celestial sphere. Just as the North and South Poles are antipodal points on Earth, two stars or phenomena in the sky can be considered antipodal if a line passing through the center of the celestial sphere connects them.
Further explanation:
Relating to or situated on the opposite side of the Earth; in astrology, it refers to points or positions that are diametrically opposed.
In astrology, “antipodal” describes locations or chart positions that directly oppose one another across the globe or zodiac. In locational astrology, an antipodal point is the place on Earth exactly opposite one’s birth location, often used in astrocartography to explore mirrored or complementary influences. For example, a person born in New York City has an antipodal location near Perth, Australia. In a natal chart, an antipodal relationship can highlight polarity, balance, or tension, similar in symbolism to planetary oppositions. Some astrologers consider antipodal points when evaluating geographical relocations, karmic opposites, or balancing energies in predictive work.
In the image above, the two points P and P' (red) are antipodal because they are ends of a diameter PP', a segment of the axis a (purple) passing through the sphere's center O (black). P and P' are the poles of a great circle g (green) whose points are equidistant from each (with a central right angle). Any great circle s (blue) passing through the poles is secondary to g.
Source: Cindy McKean, Wikipedia