| Noun | 1. | infrared - the infrared part of the electromagnetic spectrum; electromagnetic wave frequencies below the visible range; "they could sense radiation in the infrared"frequence, frequency, oftenness - the number of occurrences within a given time period (usually 1 second); "the frequency of modulation was 40 cycles per second" | |
| 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"invisible, unseeable - impossible or nearly impossible to see; imperceptible by the eye; "the invisible man"; "invisible rays"; "an invisible hinge"; "invisible mending" | |