poly·​graph | \ˈpä-lē-ˌgraf \

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 \ 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

This would start with the polygraph test and therapist’s notes, and go back 36 years. WSJ, "Democrats Face Risk in Pursuing Kavanaugh," 15 Oct. 2018 Earlier this year, President Trump ordered another hiring spree, calling for an additional 5,000 Border Patrol agents, as well as a waiver for some applicants on the polygraph test to speed up the hiring process. Skye Parrott, Marie Claire, "What It's Like to Be a Female Border Patrol Agent," 5 Dec. 2017 Ford told her husband and her therapist about her story and her trauma in 2002, long before Kavanagh was ever a glimmer in Trump's eye and, just this summer, passed a polygraph test. Michelle Ruiz, Vogue, "Brett Kavanaugh Says He Won't Back Down—But Dr. Christine Blasey Ford Says She Won't Either," 24 Sep. 2018 The frequency of these cases prompted Congress to mandate a polygraph test—which covers everything from petty crimes to potential relationships with drug cartels—as part of its vetting system for new recruits in 2010. Skye Parrott, Marie Claire, "What It's Like to Be a Female Border Patrol Agent," 5 Dec. 2017 The two polygraph experts were busted for taking a bicycle with a pink seat on a late-night joyride between bars on Mackinac Island, the Detroit News reports. Melissa Locker, Time, "Two Cops Went on a Very Silly Joy Ride on a Pink-Seated Bicycle," 27 June 2018 They were selected from a pool of about 40 applicants and went through a several-month selection process that included testing, interviews, background check, polygraph, and both medical and psychological evaluations. Sue Kiesewetter, Cincinnati.com, "Trustee: New police officers bring 'energy and enthusiasm' to Fairfield Twp.," 29 Mar. 2018 Dwyer said Ream, 69, is suspected in the other missing girl cases, was interviewed and failed a polygraph. Christina Hall, Detroit Free Press, "Dig for missing girls in Macomb Twp. halted: What now?," 15 May 2018 Lawmakers have proposed legislation that would relax the system only somewhat, waiving the polygraph for certain veterans and former security clearance holders. Tal Kopan, CNN, "Border Patrol has thousands of openings it can't fill," 6 Apr. 2018

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

3 Dec 2018

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Time Traveler for polygraph

The first known use of polygraph was in 1871

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More Definitions for polygraph



English Language Learners Definition of polygraph

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


poly·​graph | \ˈpäl-i-ˌgraf \

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 \ adjective
polygraphically \-​i-​k(ə-​)lē \ adverb


poly·​graph | \ˈpä-lē-ˌgraf \

Legal Definition of polygraph 

: an instrument that records physiological pulsations especially : lie detector

Other Words from polygraph

polygraphic \ˌpä-​lē-​ˈgra-​fik \ adjective

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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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a nest or breeding place

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