Search the Dictionary:

 
A-B-C-D-E-F-G-H-I-J-K-L-M-N-O-P-Q-R-S-T-U-V-W-X-Y-Z
 
cave
Grjótagjá caves near Mývatn lake, Iceland. Photo: Chmee2.

cave:

A naturally formed open space in rock usually open to the surface through a passageway. Limestone caves that are very large are called caverns.