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

Officers used drones, infrared technology and bloodhounds to search through the woods near the Terrapin Trail Garage, where Ashar was last seen on camera, Mitchell said. — Angie Orellana Hernandez, Washington Post, 8 Oct. 2026

This animation uses infrared imagery which depicts the most intense thunderstorms near the center of Isaias in purple and white. — Kate S. Petersen, CNN Money, 8 Oct. 2026

There’s also a 24-hour gym, saltwater pool, infrared sauna, and cold plunges. — Nikkita Nair, Condé Nast Traveler, 7 Oct. 2026

Hotel spas have become expansive hubs of self-care, providing travelers with a full range of facials and lymphatic drainage massages, plus advanced modalities like infrared saunas, cold plunges, LED beds, oxygen chambers, and cryotherapy. — Lindsay Cohn, Vogue, 7 Oct. 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