lie detector

American  

noun

1. a polygraph used to determine changes in certain body activities, as blood pressure, pulse, breathing, and perspiration, the results of which may be interpreted to indicate the truth or falsity of a person's answers under questioning.

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lie detector British  

noun

1. a polygraph used esp by a police interrogator to detect false or devious answers to questions, a sudden change in one or more involuntary physiological responses being considered a manifestation of guilt, fear, etc See polygraph galvanic skin response

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Etymology

Origin of lie detector

An Americanism dating back to 1905–10

Example Sentences

In his letter to Weber, Curtis promised to take a lie detector test after each election.

From Los Angeles Times • Mar. 25, 2026

Rhino poaching almost doubled in South Africa's Kruger National Park in 2025 compared to the previous year, despite interventions including dehorning and lie detector tests for rangers, the government said Tuesday.

From Barron's • Feb. 10, 2026

In the “Materialists” press tour, Johnson is more freely magnetic, sitting for another “Vanity Fair” lie detector test and answering cheeky, rapid-fire questions with her co-star, Pedro Pascal, for “Vogue.”

From Salon • Jun. 17, 2025

Employees in the DEA’s polygraph unit, which vets prospective agents, reported being pressured to pass candidates after they failed a lie detector test, report says.

From Los Angeles Times • Oct. 25, 2024

It's the same principle used in the police "lie detector" test, only the Damasios are interested in a different sort of truth.

From "Phineas Gage" by John Fleischman