Here is a small glossary of words commonly used in caving:

• Aven, vertical cave: Occitan term. A natural shaft in limestone formed either by dissolution or collapse of the vault of a cavity. Example: Aven d’Orgnac.
• Conduit: long, relatively narrow, low gallery.
• Calcite: calcium carbonate, the main constituent of concretions.
• Cavernicolous: animal or plant living underground.
• Chimney: vertical conduit leading upwards.
• Concretion, dripstone formation: an aggregation of matter formed by the deposition of substances dissolved in water. Underground, calcite and aragonite are most often found in various forms.

More definitions…

• Drapery: descending concretion in the form of a curtain.
• Squeeze: very narrow passage that can be negotiated.
• Straw: fine stalactite tube, sometimes several decimetres long.
• Gallery: a more or less horizontal natural underground passage.
• Cave: natural underground cavity with at least one accessible horizontal part.
• Gour: a calcite deposit around a large or small body of water, forming a natural dam.
• Karst: limestone massif in which water has carved out numerous cavities.
• Meander: generally high, narrow and very winding underground passage.
• Pitch: Vertical or sub-vertical shaft or cave waterfall that normally requires rope, ladder or equipment to pass; a term used by British cave explorers.
• Siphon: completely flooded gallery.
• Stalactite: descending concretion.
• Stalagmite: rising concretion.