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

Roman will pair a large field of view with crisp infrared vision to survey deep, vast swaths of sky. —Richard Tribou, The Orlando Sentinel, 12 June 2026

Breathwork, movement, nutrition, sleep education, and, in some clinics, near-infrared light or photobiomodulation (red-light therapy) round out the treatments. —Melinda Fulmer, Robb Report, 11 June 2026

The team found that a near-infrared resolving power of at least 40 is the minimum needed to break that degeneracy. —Paul Sutter, Space.com, 10 June 2026

In a supersonic flight configuration of the Rafale, at faster than the speed of sound (Mach 1), the MICA NG and its infrared seeker are subjected to a higher ambient temperature, according to MBDA. —Prabhat Ranjan Mishra, Interesting Engineering, 7 June 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