cavern

nouns

any large dark enclosed space

"his eyes were dark caverns"

cavern

is a type of (narrower)

a naturally enclosed space

a large cave or a large chamber in a cave

cavern

is derived from

is a type of (narrower)

a geological formation consisting of an underground enclosure with access from the surface of the ground or from the sea

hollow out as if making a cavern

cavern, cavern out