infrared

Meanings

1. 1
   adj

   using or relating to electromagnetic wavelengths longer than visible red light but shorter than microwaves

   The telescope uses an infrared detector to observe cool clouds of dust.

2. 2
   noun

   the region or radiation of the electromagnetic spectrum with wavelengths of roughly 700 nanometers to 1 millimeter

   The sensor converts invisible infrared into a temperature image.

From infra- (Latin for "below") + red, because its frequencies lie below those of visible red light. The term replaced the earlier expression calorific rays in the nineteenth century.

Topics