Cavernous

['kævənəs] or ['kævɚnəs]

(adj.) being or suggesting a cavern; 'vast cavernous chambers hollowed out of limestone' .

Checker: Lucille--From WordNet

(a.) Full of caverns; resembling a cavern or large cavity; hollow.

(a.) Filled with small cavities or cells.

(a.) Having a sound caused by a cavity.

Checker: Spenser

a. Hollow.

Checker: Norris