n. a chamber that leads to a body cavity or that connects one cavity to another. The vestibule of the vagina is the cavity in the vulva, between the two labia minora, into which the vagina, urethra, and greater vestibular glands open. The vestibule of the inner ear is the cavity of the bony labyrinth that contains the utricle and saccule (the vestibular sacs) and is connected to the semicircular canals and cochlea. —vestibularadj.