middle ear morphology trait oval window morphology trait Any measurable or observable characteristic related to the shape, structure, color or pattern of the oval opening on the medial wall of the tympanic cavity leading into the vestibule, close to the foot of the stapes. Trait.ontology VT:0004479 fenestra ovalis morphology trait fenestra vestibuli morphology trait morphology trait of the fenestra of the vestibule vestibular window morphology trait