blue light

American  

[bloo lahyt] / ˈblu ˈlaɪt /

noun

1. a band of the visible light spectrum that has a shorter wavelength and produces higher energy than other colors of light: occurring in sunlight and emitted by electronic devices that use LED technology.

2. American History, Usually Disparaging. Also Blue Light a member of a faction of the American Federalist party considered disloyal for opposing the War of 1812: so called from the claim that they flashed blue light signals to alert the British to the presence of blockade runners.

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Etymology

Origin of blue light

First recorded in 1810–15

Example Sentences

Depending on the situation, a Tesla will gently warn with a message and a flashing blue light on the center screen, buzz, or require pressure on the steering wheel.

From Barron's • May 3, 2026

Low-energy infrared photons do not have enough energy to activate electrons, while high-energy photons such as blue light lose their extra energy as heat.

From Science Daily • Mar. 28, 2026

Most of these children were born during the pandemic and spent much of their infancy quarantined indoors, their earliest socialization filtered through the blue light of tablets and television, Aguet said.

From Los Angeles Times • Jan. 27, 2026

“Melatonin is what makes you sleepy. The effect of the blue light is that it makes you more awake and alert.”

From The Wall Street Journal • Nov. 25, 2025

They emerged in a viewing room awash with blue light.

From "The Mark of Athena" by Rick Riordan