a medical device that allows a doctor to listen to your heart, lungs, or other part of your body. (Definition of stethoscope from the Cambridge Academic Content Dictionary © Cambridge University Press)

Stethoscope, medical instrument used in listening to sounds produced within the body, chiefly in the heart or lungs. It was invented by the French physician R.T.H. Laënnec, who in 1819 described the use of a perforated wooden cylinder to transmit sounds from the patient’s chest (Greek: stēthos) to the physician’s ear.