From 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]