Definition of "infrared" in English

noun

1. (uncountable) The electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation, having a wavelength between 700 nm and 1 mm.

2. (countable) A specific wavelength in this range.

3. (countable) A device that emits infrared radiation.

adjective

1. Having a wavelength in the infrared spectrum.

2. (figurative, physics) Relating to very low energies or very large distances or time spans.