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]WordNet (r) 3.0 (2006):
meatus n 1: a natural body passageway