Definition of "polygraph" [pol•y•graph]

• An instrument that simultaneously records changes in physiological processes such as heartbeat, blood pressure, and respiration, often used as a lie detector. (noun)
• To test (a criminal suspect, for example) with a polygraph. (verb-transitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "And to ask someone to take a polygraph is a major thing, but she said she was willing to do it."
• "A Mr. Hawkins of Frankford, near Philadelphia, has invented a machine which he calls a polygraph, and which carries two, three, or four pens."
• "As Radford later described his work — in polygraph tests, sworn testimony, and interviews with historians and journalists — he spent 13 months illegally obtaining NSC documents and turning them over to his superiors, with the understanding that the two admirals were, in turn, funneling the materials to the chairman of the Joint Chiefs and other top uniformed commanders."