A new word I love!
Definition of VESTIBULE
b : an enclosed entrance at the end of a railway passenger car
a : the central cavity of the bony labyrinth of the inner ear or the parts (as the saccule and utricle) 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