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

Electric fireplaces produce heat by blowing air over heated coils or with infrared light and can be used with or without the heating function engaged. — Bestreviews, Chicago Tribune, 6 Nov. 2026

On this flight, that payload was an Earth observation pod, essentially a high-resolution camera plus infrared sensors, sending images to the ground in real time. — New Atlas, 6 Nov. 2026

The front of the camera is black and holds the lens, a laser light ring, four infrared LEDs for black-and-white night vision, two microphones, and a radar sensor. — John R. Delaney, PC Magazine, 5 Nov. 2026

The team fed two independent infrared lasers into the chip, creating a partially coherent mixture. — Neetika Walter, Interesting Engineering, 4 Nov. 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