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

Multi-sensor fusion Modern military drones can carry several different types of sensors, including electro-optical cameras, infrared systems, radar, and electronic warfare equipment. — Atharva Gosavi, Interesting Engineering, 21 July 2026

Optical switches use infrared light and photoelectric sensors to detect key presses, unlike mechanical keyboards, which use metal contacts to detect how far a key is pressed. — Zackery Cuevas, PC Magazine, 21 July 2026

The new Club 27 wellness membership grants access to guests’ favorite hotel perks, including the 72-foot heated indoor lap pool, infrared sauna and steam room, outdoor sun deck, and fitness center with Peloton bikes and Technogym equipment. — Nina Ruggiero, Travel + Leisure, 20 July 2026

To image it, the researchers used near-infrared imaging hardware attached to a telescope at the Las Campanas Observatory in the Atacama Desert. — John Timmer, ArsTechnica, 16 July 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