The Collaborative International Dictionary of English v.0.48:
Chthonic \Chthon"ic\, a. [Gr. ?, ?, the earth.] Pertaining to the earth; earthy; as, chthonic religions. [1913 Webster] [The] chthonic character of the wife of Zeus. --Max M["u]ller. [1913 Webster] ChthonophagiaWordNet (r) 3.0 (2006):
chthonic adj 1: dwelling beneath the surface of the earth; "nether regions" [syn: chthonian, chthonic, nether]