bronchus

from WordNet (r) 3.0 (2006)

bronchus
    n 1: either of the two main branches of the trachea [syn:
         {bronchus}, {bronchial tube}]

from The Collaborative International Dictionary of English v.0.48

Bronchus \Bron"chus\, n.; pl. {Bronchi}. [NL., fr. Gr. ?
   windpipe. Cf. {Bronchia}.] (Anat.)
   One of the subdivisions of the trachea or windpipe; esp. one
   of the two primary divisions.
   [1913 Webster]