1. [ adjective ] 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"

Related terms: invisible
2. [ noun ] (physics) the infrared part of the electromagnetic spectrum; electromagnetic wave frequencies below the visible range
Synonyms: infrared_frequency

"they could sense radiation in the infrared"

Related terms: frequency infrared_spectrum
3. [ noun ] (physics) electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves
Synonyms: infrared_emission infrared_radiation infrared_light
Related terms: actinic_radiation
Similar spelling:   infra