from The Century Dictionary.
- noun In Pythagorean astronomy, an imaginary invisible planet continually opposing the earth and eclipsing the central fire, round which it was supposed to revolve, in common with the earth, moon, sun, certain planets, and the fixed stars.
- noun plural The inhabitants of an opposite hemisphere.
from the GNU version of the Collaborative International Dictionary of English.
- noun A hypothetical earth counter to ours, or on the opposite side of the sun.
- noun Inhabitants of opposite hemispheres.
Sorry, no etymologies found.
No longer will you see the antichthon of Plato, the focus of Philolaüs, the spheres of Aristotle, or the seven heavens of the Jews with the great waters above the vault of crystal! "
The Pythagoreans, on the other hand, attributed perfection to the number ten; but agreed in thinking that the perfect number must be somehow realized in the heavens; and knowing only of nine heavenly bodies, to make up the enumeration, they asserted “that there was an _antichthon_, or counter-earth, on the other side of the sun, invisible to us.” (