a lobby or chamber between the outer door and the interior of a building
any of various bodily cavities, esp when serving as or resembling an entrance to some other cavity or space, e.g.:
the central cavity of the bony labyrinth of the ear
the part of the mouth cavity outside the teeth and gums
vestibular /veʹstib-/ adj
vestibuled adj
[Latin vestibulum entrance, courtyard]