orifice, porta, opening - an aperture or hole opening into a bodily cavity; "the orifice into the aorta from the lower left chamber of the heart"

ear - the sense organ for hearing and equilibrium

fenestra of the vestibule, fenestra ovalis, fenestra vestibuli, oval window - fenestra that has the base of the stapes attached to it

fenestra cochleae, fenestra of the cochlea, fenestra rotunda, round window - fenestra leading into the cochlea

otolaryngology, otology - the branch of medicine concerned with the ear