n. 1 a an antechamber, hall, or lobby next to the outer door of a building. b a porch of a church etc. 2 US an enclosed entrance to a railway-carriage. 3 Anat. a a chamber or channel communicating with others. b part of the mouth outside the teeth. c the central cavity of the labyrinth of the inner ear. vestibular adj.
[ F vestibule or L vestibulum entrance-court ]