Source : Webster's Revised Unabridged Dictionary (1913)

Rhonchus \Rhon"chus\, n.; pl. {Rhonchi}. [L., a snoring, a
   croaking.] (Med.)
   An adventitious whistling or snoring sound heard on
   auscultation of the chest when the air channels are partially
   obstructed. By some writers the term rhonchus is used as
   equivalent to r[^a]le in its widest sense. See {R[^a]le}.

Source : WordNet®

rhonchus
     n : a sound like whistling or snoring that is heard with a
         stethoscope during expiration as air passes through
         obstructed channels
     [also: {rhonchi} (pl)]