Source : Webster's Revised Unabridged Dictionary (1913)

Stethoscope \Steth"o*scope\, n. [Gr. ? the breast + -scope: cf.
   F. st['e]thoscope.] (Med.)
   An instrument used in auscultation for examining the organs
   of the chest, as the heart and lungs, by conveying to the ear
   of the examiner the sounds produced in the thorax.

Stethoscope \Steth"o*scope\, v. t.
   To auscultate, or examine, with a stethoscope. --M. W.
   Savage.

Source : WordNet®

stethoscope
     n : a medical instrument for listening to the sounds generated
         inside the body