[ves.ti.bule] n [L vestibulum] (1728) 1: any of various bodily cavities esp. when serving as or resembling an entrance to some other cavity or space: as a: the central cavity of the bony labyrinth of the ear or the parts of the membranous labyrinth that it contains b: the part of the left ventricle below the aortic orifice c: the space between the labia minora containing the orifice of the urethra d: the part of the mouth cavity outside the teeth and gums
2. a: a passage, hall, or room between the outer door and the interior of a building: lobby b: an enclosed entrance at the end of a railway passenger car
3: a course that offers access (as to something new) -- ves.ti.buled adj