The Collaborative International Dictionary of English v.0.48:

Rale \R[^a]le\ (r[aum]l), n. [F. r[^a]le. Cf. Rail the bird.]
   (Med.)
   An adventitious sound, usually of morbid origin, accompanying
   the normal respiratory sounds. See Rhonchus.
   [1913 Webster]

   Note: Various kinds are distinguished by pathologists;
         differing in intensity, as loud and small; in quality,
         as moist, dry, clicking, whistling, and sonorous; and
         in origin, as tracheal, pulmonary, and pleural.
         [1913 Webster]