| a. | 1. | (Physics) Lying outside the visible spectrum at its red end; - said of rays having a longer wavelength (and thus less refrangible) than the extreme red rays, specifically those electromagnetic waves having a wavelength of between 700 nanometers and 1 millimeter. |
| 2. | relating to, using, or producing infrared radiation. | |
| 3. | affected by infrared radiation; |
| Noun | 1. | infrared - the infrared part of the electromagnetic spectrum; electromagnetic wave frequencies below the visible range; "they could sense radiation in the infrared" Synonyms: infrared frequency |
| 2. | infrared - electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves | |
| Adj. | 1. | infrared - having or employing wavelengths longer than light but shorter than radio waves; lying outside the visible spectrum at its red end; "infrared radiation"; "infrared photography" |
| (electronics) | infrared - (IR) Electromagnetic waves in the frequency range just below visible light corresponding to radiated heat. IR waves can be generated by a kind of LED and are often used for remote controls for televisions etc. and in some docking stations. |