a natural chamber, usu underground or in the side of a hill or cliff, with an opening on the surface
(used before a noun) living or found in a cave or caves
cave dweller
cave painting
Brit a formal withdrawal from a political party, or a group of people who do this
[Middle English via Old French from Latin cava, from cavus hollow; (sense 2) from cave of Adullam, where David was joined by malcontents (I Samuel 22:1, 2)]