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

Back at the safe house, Kyle and the gang are questioning Gutierrez on the polygraph while the maid, his informant in the Carrillo home, is having a much quieter chat with Kaitlyn. —Andy Andersen, Vulture, 1 Dec. 2024

In between Tapp's nine interrogations, detectives also administered seven polygraph exams. —Anne-Marie Green, Judy Rybak, CBS News, 16 June 2018

The whole group seems to accept the definite possibility that their captive is telling the truth, but Kaitlyn orders a thirty-milligram methylphenidate injection and polygraph test, just to be safe. —Andy Andersen, Vulture, 24 Nov. 2024

Williamson was later asked by sheriff’s investigators to take a polygraph test. —Jordan D. Brown, CNN, 24 Nov. 2024

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

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