poly·​graph | \ ˈpä-lē-ˌgraf How to pronounce polygraph (audio) \

Definition of polygraph

: an instrument for recording variations of several different pulsations (as of physiological variables) simultaneously — compare lie detector

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Other Words from polygraph

polygraphic \ ˌpä-​lē-​ˈgra-​fik How to pronounce polygraphic (audio) \ adjective

Synonyms for polygraph


lie detector

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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

Police say Williams passed a polygraph test, and their interviews with Williams and another person of interest in the case revealed that Williams was hardly the only person with access to the house. Robert Klemko, SI.com, "There’s More History to Antonio Brown’s History," 16 Sep. 2019 After failing a polygraph test, Watts confessed to killing Shanann, who was pregnant, in the early hours of Aug. 13. Elise Schmelzer, The Denver Post, "Christopher Watts murder investigation: Recap of the case that drew international attention to a small Colorado town," 13 Aug. 2019 There are polygraphs for sleep diagnosis, ozone therapy sessions, a neurocognitive assessment, colon hydrotherapy, NADH treatment and pelvic floor physiotherapy for women, to name but a few elements of the inside-out makeover. Kathryn Romeyn, The Hollywood Reporter, "6 Hollywood-Loved Spas and Clinics Where Stars Seek Secrets to Living Longer," 8 Aug. 2019 An extensive application, involving a polygraph test that more than 40% of applicants fail, makes the hiring process extremely slow. Justin Rohrlich, Quartz, "“Bodies and minds are breaking down”: Inside US border agency’s suicide crisis," 2 July 2019 Two out of three applicants fail its polygraph, according to Reardon, more than double the average failure rate for other federal law enforcement agencies. Nick Miroff, Washington Post, "U.S. customs agency is so short-staffed, it’s sending officers from airports to the Mexican border," 19 Jan. 2018 The chief also testified O’Neill passed a polygraph test. Bill Ruthhart, chicagotribune.com, "South Bend Mayor Pete Buttigieg speaking at Rev. Jesse Jackson’s Rainbow/PUSH annual convention," 2 July 2019 Moore said in a December 2017 affidavit after the polygraph test. Paul Gattis | Pgattis@al.com, al.com, "Roy Moore ‘likely failed’ polygraph test, Corfman says," 1 July 2019 The polygraph was never rescheduled and the killing eventually went cold. Harriet Sokmensuer, PEOPLE.com, "Widow, 84, Charged With Murder 35 Years After Husband's Death — and TV Show Helped Solve Case," 11 July 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'polygraph.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of polygraph

1871, in the meaning defined above

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Statistics for polygraph

Last Updated

24 Sep 2019

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The first known use of polygraph was in 1871

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English Language Learners Definition of polygraph

US : a test that is done with a lie detector to see if someone is telling the truth


poly·​graph | \ ˈpäl-i-ˌgraf How to pronounce polygraph (audio) \

Medical Definition of polygraph

: an instrument for simultaneously recording variations of several different pulsations (as of the pulse, blood pressure, and respiration) — see lie detector

Other Words from polygraph

polygraphic \ ˌpäl-​i-​ˈgraf-​ik How to pronounce polygraphic (audio) \ adjective
polygraphically \ -​i-​k(ə-​)lē How to pronounce polygraphically (audio) \ adverb


poly·​graph | \ ˈpä-lē-ˌgraf How to pronounce polygraph (audio) \

Legal Definition of polygraph

: an instrument that records physiological pulsations especially : lie detector

Other Words from polygraph

polygraphic \ ˌpä-​lē-​ˈgra-​fik How to pronounce polygraphic (audio) \ adjective

More from Merriam-Webster on polygraph

Rhyming Dictionary: Words that rhyme with polygraph

Thesaurus: All synonyms and antonyms for polygraph

Britannica.com: Encyclopedia article about polygraph

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