lie detector

noun

: a polygraph for detecting physiological evidence (such as change in heart rate) of the tension that accompanies lying

Synonyms

• polygraph

Examples of lie detector in a Sentence

The murder suspect failed a lie detector test.

hooked the suspect up to a lie detector before interrogating him about the robbery

Recent Examples on the Web

Thanks to an assist from Dr. Gabriela Torabi, the president’s therapist, Xavier is saved from a lie detector test that Samantha is closely monitoring. —Maggie Fremont, Vulture, 31 Jan. 2025

Later, he’s locked in an interrogation room and connected to lie detectors, being questioned by a character played by Krys Marshall, and nudged to lie about his feelings by another (Sarah Shahi) — who claims to have a message from Cal himself. —Proma Khosla, IndieWire, 16 Jan. 2025

Those who tried Silk vs. milk could then take a lie detector done by polygraph specialist John Grogan. —Victoria Uwumarogie, Essence, 16 Jan. 2025

According to one lawyer, his client proved his innocence with a lie detector test. —Michael Gfoeller and David H. Rundell, Newsweek, 16 Jan. 2025

Word History

First Known Use

1909, in the meaning defined above

Kids Definition

lie detector

noun

: an instrument for detecting bodily changes (as an increase in heart rate) that are considered to go along with lying

Medical Definition

lie detector

noun

ˈlī-di-ˌtek-tər 

: a polygraph for detecting physiological evidence (as change in heart rate) of the tension that accompanies lying

Legal Definition

lie detector

noun

lie de·​tec·​tor

: an instrument for detecting physiological evidence of the tension that accompanies lying compare polygraph