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

This ancient galaxy has ionized carbon that seems to be unusually faint compared to how bright the galaxy is in infrared. —Robert Lea, Space.com, 7 July 2025

For hands-free operation, there’s an infrared remote and the FiiO Control app enables the unit to be controlled remotely. —Mark Sparrow, Forbes.com, 2 July 2025

The source of the infrared light is located within three dust rings observed surrounding TWA 7. —Julia Jacobo, ABC News, 2 July 2025

Building amenities include a speakeasy lounge, amenity deck with a pool and a hot tub, wellness center with cold plunge tubs and an infrared sauna, gym and co-working lounges. —Molly Davis, The Tennessean, 2 July 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