polygraph

noun

poly·​graph ˈpä-lē-ˌgraf 

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

polygraphic

ˌpä-lē-ˈgra-fik 

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.

Synonyms

• lie detector

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

Others suggested that any joke made by the leader about the upcoming season was delivered in poor taste, offending agency staff already suffering from low morale amid a flurry of resignations, firings, leadership overhauls and polygraph tests distributed to staffers. —Nicole Sganga, CBS News, 2 June 2025

In November, Dove pleaded guilty in Gaston County to a dozen felony charges related to illegally accessing police computer systems and helping someone deceive a polygraph test, The Gaston Gazette reported. —Julia Coin, Charlotte Observer, 30 May 2025

The lie detector test was conducted by polygraph expert Brett Bartlett, a retired police officer with 20 years of experience in law enforcement. —Stephanie Nolasco, FOXNews.com, 24 May 2025

James told the court that in his first year working for Combs, some money went missing and Combs had a former FBI agent who specialized in polygraphs to interview him. —Doha Madani, NBC news, 20 May 2025

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

Rhymes for polygraph

• autograph
• biograph
• cenotaph
• chronograph
• epigraph
• epitaph
• hodograph
• holograph
• hydrograph
• lithograph
• micrograph
• monograph

Kids Definition

polygraph

noun

poly·​graph ˈpäl-i-ˌgraf 

: 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 

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

polygraphic

ˌpäl-i-ˈgraf-ik 

adjective

polygraphically

-i-k(ə-)lē 

adverb

Legal Definition

polygraph

noun

poly·​graph ˈpä-lē-ˌgraf 

: an instrument that records physiological pulsations

especially : lie detector

polygraphic

ˌpä-lē-ˈgra-fik 

adjective