noun. the part of the electromagnetic spectrum from 0.5 nm to 400 nm. The upper range of the ultraviolet part of the spectrum is just beneath the wavelengths interpreted as blue. Ultraviolet stimulants can be viewed by some fish and insects because they have photopigments inside their retinas which are vulnerable to these wavelengths.
ULTRAVIOLET (UV): "Some tanning salons claim to have tanning beds that do not contain the same harmful ultraviolet rays that natural sunlight does."