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

In 2020, Longcore co-published a study linking artificial night light, including blue light emitted by LEDs, to cancer.

From Los Angeles Times • May 8, 2026

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

Ratcliff said blue light police pursuits were rare and there were plenty of trained officers able to carry out emergency responses while the training is rolled out.

From BBC • Jan. 7, 2026

The stadium is bathed in dim blue light.

From "Warcross" by Marie Lu