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.

---

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

---

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

She said a Combs aide administered a lie detector test to her.

From Los Angeles Times • May 28, 2025

“These games are fake! Kasparov should answer my charges! He should be put through a lie detector test, and then the whole world will see what a liar he is!”

From "Endgame" by Frank Brady