Chthonic

Chthonic  literally means "subterranean", but the word in English describes deities or spirits of the underworld, especially in Ancient Greek religion. The Greek word khthon is one of several for "earth"; it typically refers to that which is under the earth,[2]rather than the living surface of the land (as Gaia or Ge does), or the land as territory (as khora χώραdoes).[
(UK: /ˈkθɒnɪk/, US: /ˈθɒnɪk/ from Ancient Greek: χθόνιος, translit. khthonios [kʰtʰónios], "in, under, or beneath the earth", from χθών khthōn "earth")[1]