outer ear (external ear) The part of the ear external to the tympanum (eardrum). It is present in mammals, birds, and some reptiles and consists of a tube (the external auditory meatus) that directs sound waves onto the tympanum. In mammals it may include an external pinna, which extends beyond the skull.

outer ear (owt-er) n. the pinna and the external auditory meatus of the ear.