Relating to or existing in the earth or underground; subterranean or infernal in character, especially in mythology.
From Greek katachthonios, combining kata- 'down' with chthon- (from chthon 'earth'), plus -ian. Related to chthonic deities in ancient mythology.
The chthonic (earth) gods of ancient Greece were catachthonian powers ruling the underworld and buried things—Hades and Persephone are the most famous catachthonian deities in mythology.
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