Glossary of Karst and Cave Terms
Based on "A Lexicon of Cave and Karst Terminology with Special to Environmental Karst Hydrology" EPA/600/R-02/003, 2002, EPA: Washington, DC., Speleogenesis Glossary includes 2699 cave & karst terms
1. In speleology, a natural opening above the floor of a passage or a room, giving access to an adjoining cavity or to the surface; larger and less symmetrical than a porthole. 2. The opening under the arch of a small natural bridge . See karst window.