Emily Dickinson Lexicon

CAV'ERN, n. [L. caverna; Sp. Port. and It. id. This word seems to be composed of cavus, and the Sax. ærn, a secret place. See Tavern and Barn.]

A deep, hollow place in the earth. In general, it differs from cave in greater depth, and in being applied most usually to natural hollows or chasms. Earth with its caverns dark and deep. – Watts.