ultraviolet

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of or relating to electromagnetic radiation between violet visible light and x-rays in the electromagnetic spectrum, having frequencies between 790 terahertz and 30 petahertz and wavelengths between 380 nanometers and 10 nanometers.
• adjective Of or relating to a light bulb that emits ultraviolet radiation.
• noun The ultraviolet range of electromagnetic radiation.

from The Century Dictionary.

• Beyond the violet: used of the invisible rays of the spectrum which are more refrangible than the violet, and consequently lie beyond them. See spectrum.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Physics) Lying outside the visible spectrum at its blue-violet end; -- said of light more refrangible (i. e. having a shorter wavelength) than the extreme violet rays of the visible spectrum. Electromagnetic radiation with wavelengths shorter than those of ultrviolet light are not usually considered as light waves, but are classified differently. The ultraviolet region of the electromagnetic spectrum is generally considered as comprising those electromagnetic emissions with wavelengths lying between those of visible light and those of X-rays, i. e. between 4000 Angstroms and 100 Angstroms.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective of electromagnetic radiation beyond (higher in frequency than) light visible to the human eye; radiation with wavelengths from 380 nanometre - 10 nanometre
• noun Ultraviolet colour.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective having or employing wavelengths shorter than light but longer than X-rays; lying outside the visible spectrum at its violet end
• noun radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays