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 team observed the active and inactive periods of these cnidarians using infrared cameras and movement-tracking software. —New Atlas, 24 Jan. 2026

Cabin cosplay is on full display here with an infrared heater that lands somewhere between looking like a record player and a wood fire stove. —Julia Harrison, Architectural Digest, 23 Jan. 2026

Thermal Imaging Systems And Frigid Temperatures Thermal imaging systems detect the infrared radiation emitted by all objects with a temperature above absolute zero, producing images based on heat differentials rather than visible light. —Vikram Mittal, Forbes.com, 22 Jan. 2026

Among other things, the center has been expanded to include an infrared sauna, an ice pool, an upgrade for the gym and bright treatment rooms with their own small Zen gardens, one of which is reserved specifically for Ayurveda therapies. —Condé Nast, Condé Nast Traveler, 22 Jan. 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