What does infrared mean?
Infrared is electromagnetic radiation that lies beyond the red end of the visible spectrum, with wavelengths shorter than those of microwaves and longer than those of visible light. Although it is not normally visible to humans, it can be detected with specialized instruments and is often associated with heat. Infrared technology is used in thermal cameras, night-vision devices, remote controls, spectroscopy, and astronomy. As an adjective, infrared describes radiation, sensors, images, or observations involving this part of the electromagnetic spectrum. The term comes from Latin infra, meaning “below,” and red, referring to its position beyond visible red light. It is a useful word in science, technology, medicine, security, and environmental research, where it distinguishes a specific range of radiation from visible light and from other forms of electromagnetic energy.
Relating to infrared radiation or to equipment, imaging, or research that uses it.
"The laboratory purchased a new infrared detector for its astronomy programme."
Common in technical and scientific contexts, especially in combinations such as infrared radiation, infrared camera, and infrared spectroscopy.
Electromagnetic radiation with wavelengths longer than visible red light and shorter than microwaves, commonly associated with heat.
"The thermal camera displays infrared as a pattern of different colours."
Usually uncountable in general usage. It can also function attributively in compound nouns such as infrared detector and infrared imaging.
The noun is normally uncountable; the plural is uncommon and is used mainly when referring to separate infrared sources or devices.
"The observatory detected infrareds from several nearby galaxies."
Infrared means “below red”: it is the invisible radiation that reveals warmth rather than colour.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does infrared come from?
Infrared was formed in the 19th century from Latin infra, meaning “below” or “beneath,” and red, the name of the visible colour at the long-wavelength end of the spectrum. The compound literally means “below red,” indicating radiation with longer wavelengths than red light. Its development followed the identification of infrared radiation and the expansion of the concept of the electromagnetic spectrum.
How infrared is actually used
The noun is normally used in the uncountable sense, especially in scientific and technical contexts. The adjective commonly occurs in combinations such as infrared radiation, infrared camera, and infrared spectroscopy. In everyday language, infrared sometimes refers loosely to heat radiation or thermal imaging.
Easily confused with infrared
Infrared lies beyond the red end of the visible spectrum, while ultraviolet lies beyond the violet end.