The Collaborative International Dictionary of English v.0.48:

Bronchitis \Bron*chi"tis\, n. [Bronchus + -itis.] (Med.)
   Inflammation, acute or chronic, of the bronchial tubes or any
   part of them.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bronchitis
    n 1: inflammation of the membranes lining the bronchial tubes