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

The satellites detect this heat using sensitive, infrared sensors and send an alert within seconds. —Aaron Brynildson, The Conversation, 21 Mar. 2026

Elsewhere, the home leans into a life of ease and leisure with a private gym, infrared sauna, decorative fireplaces, and two laundry rooms tucked discreetly out of view. —Abby Montanez, Robb Report, 19 Mar. 2026

Omnilux’s flexible silicone face mask uses two wavelengths of red and infrared light to target fine lines, wrinkles, and hyperpigmentation. —Conçetta Ciarlo, Vogue, 19 Mar. 2026

There are also infrared varieties, which could help eliminate muscle or joint pain. —Bestreviews, Mercury News, 18 Mar. 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