1. an antechamber, hall, or lobby next to the outer door of a building.
▪ an enclosed entrance compartment in a railway carriage.
2. a chamber or channel opening into another.
▪ the central cavity of the labyrinth of the inner ear.
▪ the part of the mouth outside the teeth.
▪ the space in the vulva into which both the urethra and vagina open.
Word Originearly 17th century (denoting the space in front of the main entrance of a classical Roman or Greek building): from French, or from Latin vestibulum ‘entrance court’.