the longer wavelengths of electromagnetic radiation in the infrared region of the spectrum, beyond the red end of the visible spectrum, from 50 to 1000 micrometers. Abbreviation:FIR
far-red radiation (fär'rěd') n. Electromagnetic radiation having the longest wavelengths in the infrared region, between approximately 50 and 1,000 micrometers. Also called far-infrared radiation.
far-infrared radiation (fär'ĭn'frə-rěd') Pronunciation Key
Infrared electromagnetic radiation of very long wavelengths, in the range of 2-50 microns. It is used in medicine to provide a penetrating heat to the body. Also called far-red radiation.