infrared (Adjective) — Having or employing wavelengths longer than light but shorter than radio waves; lying outside the visible spectrum at its red end. ex. "infrared radiation" ex. "infrared photography"
infrared (Noun) — The infrared region of the electromagnetic spectrum; electromagnetic wave frequencies below the visible range. ex. "they could sense radiation in the infrared"
infrared (Noun) — Electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves.