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

Modern infrared observatories such as the James Webb Space Telescope can detect these cooler, fainter stars far more effectively than optical telescopes, helping astronomers refine estimates of the galaxy’s true stellar population. — Kaif Shaikh, Interesting Engineering, 7 July 2026

Euclid is equipped with cameras that can see both visible light and light in the near-infrared range. — Adam Kovac, Scientific American, 7 July 2026

Some films also filter specific wavelengths, allowing visible light to pass while reducing heat-producing infrared radiation. — Nafeesah Allen, Better Homes & Gardens, 7 July 2026

In fact, with its ultra-sensitive infrared vision, the JWST has been able to peer into the heart and inner workings of Centaurus A like no telescope that has gone before. — Robert Lea, Space.com, 7 July 2026

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