/in'freuh red"/ , n.
1. the part of the invisible spectrum that is contiguous to the red end of the visible spectrum and that comprises electromagnetic radiation of wavelengths from 800 nm to 1 mm.
2. noting or pertaining to the infrared or its component rays: infrared radiation. Cf. ultraviolet .
Also, infra-red .
[ 1825-35; INFRA- + RED 1 ]