meatus

from WordNet (r) 3.0 (2006)

meatus
    n 1: a natural body passageway

from The Collaborative International Dictionary of English v.0.48

Meatus \Me*a"tus\, n. sing. & pl.; E. pl. {Meatuses}. [L., a
   going, passage, fr. meare to go.] (Anat.)
   A natural passage or canal; as, the external auditory meatus.
   See Illust. of {Ear}.
   [1913 Webster]