Chthonic (UK /ˈkθɒnɪk/, US /ˈθɒnɪk/ from Greek χθόνιος khthonios [kʰtʰónios], "in, under, or beneath the earth", from χθών khthōn "earth") literally means "subterranean". The translation of meaning discusses deities or spirits of the underworld, especially in Greek religion. The Greek word khthon is one of several for "earth"; it typically refers to the interior of the soil, rather than the living surface of the land (as Gaia or Ge does), or the land as territory (as khora (χώρα) does).
Chthonic, which is a form of khthonie and khthonios, has a precise technical meaning in Greek, referring primarily to the manner and method of offering sacrifices to specific deity or deities, generally referred to as chthonic or chthonian deities. These include, but are perhaps not strictly limited to, Demeter and Hades in classical mythology.
Nocturnal ritual sacrifice was a common practice in many chthonic cults. When the sacrifice was a living creature, the animal was placed in a bothros (βόθρος, "pit") or megaron (μέγαρον, "sunken chamber"). In some Greek chthonic cults, the animal was sacrificed on a raised bomos (βωμός, "altar"). Offerings were usually burned whole or buried rather than being cooked and shared among the worshippers.