cave

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A hollow or natural passage under or into the earth, especially one with an opening to the surface.
• noun A storage cellar, especially for wine.
• intransitive verb To dig or hollow out.
• intransitive verb To cause to collapse or fall in. Often used with in:
• intransitive verb To fall in; collapse. Often used with in:
• intransitive verb To give up all opposition; yield. Often used with in:
• intransitive verb To explore caves.

from The Century Dictionary.

• To make hollow; hollow out.
• To dwell in a cave.
• To fall in and leave a hollow, as earth on the side of a well or pit: absolutely, or with in: as, the earth began to cave.
• Figuratively, to break down; yield; give up; submit; knock under: absolutely, or with in: as, at this he caved.
• noun A hollow place in the earth; especially, a natural cavity of considerable size, extending more or less horizontally into a hill or mountain; a cavern; a den.
• noun A cellar; a subterranean chamber.
• noun Any hollow place or part; a cavity.
• noun The ash-pit of a glass-furnace.
• noun [capitalized] A name given to a party in the British Parliament who seceded from the Liberals on the reform bill introduced by them in 1866. See Adullamite.
• noun Any small faction of seceders or dissidents in Parliament.
• noun A toss, as of the head.
• To toss or pitch: as, to cave hay.
• To toss in a threatening or haughty manner: as, to cave the horns (said of horned cattle); to cave the head.
• To clean (threshed grain) by tossing or raking (it) on a barn-floor or a threshing-floor.
• To move; rush.
• To sink; be plunged or buried.
• noun A cave-in.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb obsolete To make hollow; to scoop out.
• intransitive verb obsolete To dwell in a cave.
• intransitive verb To fall in or down. Hence (Slang), to retreat from a position; to give way; to yield in a disputed matter.
• intransitive verb [Slang] To submit; to yield.
• noun A hollow place in the earth, either natural or artificial; a subterraneous cavity; a cavern; a den.
• noun obsolete Any hollow place, or part; a cavity.
• noun (Eng. Politics) A coalition or group of seceders from a political party, as from the Liberal party in England in 1866. See Adullam, Cave of, in the Dictionary of Noted Names in Fiction.
• noun (Zoöl.) a very large fossil bear (Ursus spelæus) similar to the grizzly bear, but large; common in European caves.
• noun a savage of prehistoric times whose dwelling place was a cave.
• noun (Zoöl.) a fossil hyena found abundanty in British caves, now usually regarded as a large variety of the living African spotted hyena.
• noun (Zoöl.) a fossil lion found in the caves of Europe, believed to be a large variety of the African lion.
• noun See under Bone.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A large, naturally-occurring cavity formed underground, or in the face of a cliff or a hillside.
• noun A hole, depression, or gap in earth or rock, whether natural or man-made.
• noun A storage cellar, especially for wine or cheese.
• noun A place of retreat, such as a man cave.
• noun caving A naturally-occurring cavity in bedrock which is large enough to be entered by an adult.
• noun nuclear physics A shielded area where nuclear experiments can be carried out.
• noun drilling, uncountable Debris, particularly broken rock, which falls into a drill hole and interferes with drilling.
• noun mining A collapse or cave-in.
• noun figuratively The vagina.
• noun slang, politics, often "Cave" A group that breaks from a larger political party or faction on a particular issue.
• verb To surrender.
• verb To collapse.
• verb To hollow out or undermine.
• verb To engage in the recreational exploration of caves; to spelunk.