polygraph

noun

poly·​graph ˈpä-lē-ˌgraf How to pronounce polygraph (audio)
: an instrument for recording variations of several different pulsations (as of physiological variables) simultaneously compare lie detector
polygraphic adjective

Did you know?

With its graph- root, polygraph indicates that it writes out several different results. A polygraph's output consists of a set of squiggly lines on a computer screen, each indicating one function being tested. The functions most commonly measured are blood pressure, breathing rate, pulse, and perspiration, all of which tend to increase when you lie. Polygraphs have been in use since 1924, and have gotten more sensitive over the years, though many experts still believe that they're unreliable and that a prepared liar can fool the machine. They're used not only for law enforcement but perhaps more often by employers--often the police department itself!--who don't want to hire someone who has broken the law in the past but won't admit to it.

Examples of polygraph in a Sentence

They hooked him up to the polygraph and began the test. She was asked to take a polygraph.
Recent Examples on the Web On Friday, Pryor, represented by attorney Barbra Stern, filed a formal complaint with the city, accusing Glassman of verbal harassment and volunteering to take a polygraph. Steve Bousquet, Sun Sentinel, 13 Jan. 2024 Of all people who take Vanity Fair’s lie detector, Julia Fox would know how to confuse a polygraph. Bethy Squires, Vulture, 25 Oct. 2023 Smith had yet to undergo a polygraph test — Streever did not want to do it immediately as Smith was cooperating in the investigation. Eric J. Greenberg, Rolling Stone, 5 Aug. 2023 There even may have been prosecutorial misconduct—a state lawyer misleading a judge about the outcome of one of the brothers’ polygraph tests. Seyward Darby, Longreads, 10 Jan. 2024 The ruling to restore Wentz's rights to see his children appeared to include a request by the court for both parents to undergo polygraph tests about the knife allegation. David K. Li, NBC News, 3 Jan. 2024 Stix started a monthly column, Working Knowledge, that gave the reader a peek at the design and function of common technologies, from polygraph machines to Velcro. Gary Stix, Scientific American, 17 Nov. 2023 Vance agreed to take a polygraph test, but then didn't show up for the interview, detectives said. Cara Tabachnick, CBS News, 12 Jan. 2024 Titled Casey Anthony’s Parents: The Lie Detector Test, the true crime series — which premiered on Jan. 4 this year — spotlight George and his wife Cindy, who agree to undergo polygraph tests on-camera to answer lingering questions about his involvement in their granddaughter's death. Kelsie Gibson, Peoplemag, 5 Jan. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'polygraph.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

borrowed from French polygraphe, from poly- poly- + -graphe -graph

Note: As a word for such an instrument, polygraphe was apparently introduced by the French physiologist and inventor Étienne-Jules Maret (1830-1904). Compare "Des appareils enregistreurs en biologie," part 6 of "Histoire naturelle des corps organisés," Revue des cours scientifiques de la France et de l'étranger, 4. annéee (1867), p. 695: "Je vais mettre sous vos yeux l'enregistreur perfectionné que j'emploie aujourd'hui dans un grand nombre de circonstances. J'appelle polygraphe cet appareil, qui peut fournir le graphique d'un grand nombre de phénomènes différents." ("I am going to place before your eyes a perfected recording device that I have used in a great number of situations. I am calling this device a polygraph, which can provide a graphic record of a great number of different phenomena.") The word polygraph had been used earlier in English for a voluminous or versatile writer (after Greek polýgraphos "writing much"), an imitator, and an instrument resembling a pantograph.

First Known Use

1871, in the meaning defined above

Time Traveler
The first known use of polygraph was in 1871

Dictionary Entries Near polygraph

Cite this Entry

“Polygraph.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/polygraph. Accessed 19 Mar. 2024.

Kids Definition

polygraph

noun
poly·​graph ˈpäl-i-ˌgraf How to pronounce polygraph (audio)
: an instrument for recording changes in several bodily functions (as blood pressure and rate of breathing) at the same time
compare lie detector

Medical Definition

polygraph

noun
poly·​graph ˈpäl-i-ˌgraf How to pronounce polygraph (audio)
: an instrument for simultaneously recording variations of several different pulsations (as of the pulse, blood pressure, and respiration) see lie detector
polygraphic adjective
polygraphically adverb

Legal Definition

polygraph

noun
poly·​graph ˈpä-lē-ˌgraf How to pronounce polygraph (audio)
: an instrument that records physiological pulsations
especially : lie detector
polygraphic adjective

More from Merriam-Webster on polygraph

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!