The Collaborative International Dictionary of English v.0.48:

Stethoscope \Steth"o*scope\ (st[e^]th"[-o]*sk[=o]p), n. [Gr.
   sth^qos 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.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Stethoscope \Steth"o*scope\, v. t.
   To auscultate, or examine, with a stethoscope. --M. W.
   Savage.
   [1913 Webster] Stethoscopic

WordNet (r) 3.0 (2006):

stethoscope
    n 1: a medical instrument for listening to the sounds generated
         inside the body