Cavernous

Etymology

From Latin "cavernosus," from "caverna" ("cave, hollow"), which comes from "cavus" ("hollow"). The word describes spaces that feel cave-like: vast, deep, and empty within.

adjective · /KAV-ur-nus/
Resembling a cavern in being vast, deep, and hollow.
What it names
The word for a space so large and echoing that it feels like a cave — a great hall, an empty warehouse, a gaping mouth.
Example
Their footsteps echoed across the cavernous, empty hangar.
Related idea
Voluminous means having great volume or bulk; cavernous specifically evokes a hollow, cave-like emptiness.