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

Outdoor sauna options range from barrel and cabin builds to portable infrared tents at different price points, and most require planning for electrical hookups. — Lauren Schuster, Fort Worth Star-Telegram, 23 Oct. 2026

Each has an ofuro tub, steam shower, infrared sauna, relaxing area to take tea and fruit after a treatment, and an outside garden area with a plunge pool and an outdoor shower. — Condé Nast, Condé Nast Traveler, 23 Oct. 2026

The photos show a full look at the upcoming Deep Royal Blue/Black colorway, which also blends in portions of light ice blue and infrared accents. — Riley Jones, Footwear News, 22 Oct. 2026

The 6,200-square-foot venue spans two levels and features a 700-square-foot dry sauna, an infrared sauna and a 46-degree cold plunge, with dim communal areas built in to encourage guests to linger and talk. — Samantha Agate, Miami Herald, 20 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