cavernously

adv

1. In a cavernous manner; like a cavern.

   “The lurid unearthly glow still hovered in the shadowy chamber, lighting ghostlily the dead face of Thugra Khotan, which seemed to grin mirthlessly and cavernously at them.”

2. In a cavernous manner; sounding deep, hollow, or echoey.

   “...the mother of the boy was alarmed beyond measure at Jimmie's curious illness, which caused him to lie on the rug in front of the fire and groan cavernously.”