Simple Definition of polygraph
: a test that is done with a lie detector to see if someone is telling the truth
Examples of polygraph in a sentence
They hooked him up to the polygraph and began the test.
She was asked to take a polygraph.
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.
First Known Use of polygraph
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
Seen and Heard
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