apparatus - (anatomy) a group of body parts that work together to perform a given function; "the breathing apparatus"

auditory system - the sensory system for hearing

inner ear, internal ear, labyrinth - a complex system of interconnecting cavities; concerned with hearing and equilibrium

external ear, outer ear - the part of the ear visible externally

middle ear, tympanic cavity, tympanum - the main cavity of the ear; between the eardrum and the inner ear

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