infrared

adjective

in·​fra·​red ˌin-frə-ˈred 

-(ˌ)frä-,

-fə-

1

: situated outside the visible spectrum at its red end

—used of radiation having a wavelength between about 700 nanometers and 1 millimeter

2

: relating to, producing, or employing infrared radiation

infrared therapy

3

: sensitive to infrared radiation

infrared sensors that detect body heat

infrared noun

Examples of infrared in a Sentence

Recent Examples on the Web

Using a technique called spectroscopy, scientists can split the infrared light from stars and galaxies into different colors, similar to how sunlight hitting a prism separates into a rainbow of visible hues. —Denise Chow, NBC News, 26 Feb. 2025

Every six months, the telescope will create a scan of the entire sky in 102 infrared colors, differentiating hundreds of millions of galaxies by their ancient light and heat signatures and compiling them into one complete map of the universe. —Stephen J. Beard, USA TODAY, 24 Feb. 2025

Add-ons include a microcurrent lift and an infrared pulsed electromagnetic therapy mat alongside diamond collagen masks. —Kate Donnelly, Forbes, 24 Feb. 2025

Its infrared optics have looked deep into the universe's past, observed distant galaxies and exoplanets, and even peered at our own local solar system planets closer to home. —Tariq Malik, Space.com, 21 Feb. 2025

Word History

First Known Use

1881, in the meaning defined at sense 1

Phrases Containing infrared

• far-infrared
• near-infrared

Rhymes for infrared

• abovesaid
• aforesaid
• arrowhead
• casinghead
• copperhead
• figurehead
• fountainhead
• gingerbread
• hammerhead
• leatherhead
• letterhead
• loggerhead

Kids Definition

infrared

adjective

in·​fra·​red ˌin-frə-ˈred 

-(ˌ)frä-

: being, relating to, producing, or using rays like light but lying outside the visible spectrum at its red end

infrared radiation

infrared noun

Medical Definition

infrared

1 of 2 adjective

in·​fra·​red ˌin-frə-ˈred 

1

: lying outside the visible spectrum at its red end

—used of radiation having a wavelength between about 700 nanometers and 1 millimeter

2

: relating to, producing, or employing infrared radiation

infrared therapy

infrared

2 of 2 noun

: infrared radiation