1. a machine that records changes in blood pressure, pulse, breathing, and skin conductivity while a person answers questions, used as a lie detector
2. an instrument that simultaneously records several different bodily functions
Usage: medical; technical

Examples

• The suspect agreed to take a polygraph test to prove his innocence.
• Police departments often use polygraph examinations during investigations.
• The polygraph showed irregular patterns when he answered certain questions.
• She passed the polygraph test with no signs of deception.
• The results of polygraph tests are not always admissible in court.
• The technician calibrated the polygraph machine before the session.
• Many employers require polygraph screening for sensitive positions.