1. Broadly, a passage is any negotiable part of cave system, though the usage is commonly restricted to those elements that tend towards the horizontal rather than vertical or sub-vertical sections. Cave passages very in size and shape, with the latter relating to the mode of origin and providing evidence of the nature of cave development mechanisms. Perhaps the largest passage in the world is Deer Cave, which is up to 170m wide and 120m high, in the Mulu karst of Sarawak . 2. A comparatively small underground opening made along fractures, fissures, and bedding-plane partings by running water but through which it is possible to pass . 3. In a cave, the opening between rooms or chambers . Synonyms: (French.) galerie; (German.) Gallerie, Stollen; (Greek.) ypohios thiothos; (Italian.) cunicolo, galleria; (Russian.) hod; (Spanish.) galeria; (Turkish.) gecit; (Yugoslavian.) galerija. See also chamber; room.