polygraph
n. a device that measures and records several physiological indicators of stress, such as heart rate, blood pressure, and galvanic skin response. The instrument has been widely used in the interrogation of criminal suspects and in employee screening to measure marked physiological reactions to questions about such issues as theft, sexual deviation, or untruthfulness. It has been colloquially referred to as a lie detector, although no one has ever documented a close relation between physiological patterns and deceptive behavior. The accuracy of polygraph examinations is controversial, and the results are not accepted as evidence in many U.S. courts of law. [invented in 1917 by U.S. experimental psychologist William Marston (1893–1947)]