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

Radar extends surveillance over longer distances, electro-optical and infrared cameras help identify targets visually, and commanclod software brings those data streams together for faster decision-making. — Aamir Khollam, Interesting Engineering, 29 July 2026

Navigating multistory halls, stairs and dark spaces, the quadruped uses infrared cameras and acoustic sensors to detect overheating equipment and subtle gas leaks. — Arthur Zaczkiewicz, Footwear News, 28 July 2026

What to read next The new technique uses infrared thermal images and existing computer models to reconstruct a map of distortions across the mirror's surface. — Sharmila Kuthunur, Space.com, 25 July 2026

Kane County Search and Rescue launched an overnight search, deploying ground crews, drones equipped with forward-looking infrared technology and search dogs, but Guinn was not found. — Anthony Thompson, USA Today, 25 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