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

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

But she also recently revealed in a Vanity Fair lie detector test that she failed a few exams along the way, blaming ChatGPT for being an unreliable study buddy.

From Salon • Nov. 6, 2025

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

From Los Angeles Times • May 28, 2025

Is there a better spot for a guest actor on television than “Poker Face,” the Peacock mystery series starring Natasha Lyonne as a crime-solving human lie detector?

From Los Angeles Times • May 15, 2025

I imagined the secret police of America would strap him to a lie detector and say, “Have you now, or ever before, played tag, freeze tag, blob tag, or oonch neech with Iranians?”

From "Everything Sad Is Untrue" by Daniel Nayeri