cavern
//ˈkæv.ərn//
Noun
cavernSingular
cavernsPlural
1
A large, deep cave or underground chamber, often formed naturally by geological processes.
The explorers discovered a hidden cavern deep within the mountain.
2
A vast, hollow space or void, used figuratively to describe something immense and empty.
After losing his job, he felt a cavern of emptiness in his heart.