| 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-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. |
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