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

However, this innovative material completely erases thermal signatures from infrared screens by altering how heat is emitted and detected. — Mrigakshi Dixit, Interesting Engineering, 14 July 2026

There are four infrared cameras that track the motion of his head. — Ashley Portillo, CBS News, 13 July 2026

In a fire update posted Monday morning, the USWFS estimated the fire at 6,805 acres based on an infrared flight conducted Sunday night. — Shannon Tyler, Idaho Statesman, 13 July 2026

On Earth, greenhouse gases in the atmosphere, including molecules of carbon dioxide, methane and water vapor, absorb and trap some of this infrared radiation, acting like a blanket around the planet and keeping the surface warm. — Vahe Peroomian, The Conversation, 13 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