ultraviolet -
having or employing wavelengths shorter than light but longer than X-rays; lying outside the visible spectrum at its violet end; "ultraviolet radiation"; "an ultraviolet lamp"
unseeable,
invisible impossible or nearly impossible to see; imperceptible by the eye; "the invisible man"; "invisible rays"; "an invisible hinge"; "invisible mending"
ultraviolet -
Of electromagnetic radiation beyond higher in frequency than light visible to the human eye; radiation with wavelengths from 380 nanometre - 10 nanometre.
Wikipedia
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3eV to 124 eV. It is so named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. UV light is found in sunlight and is emitted by electric arcs and specialized lights such as black lights.
OmegaWiki Dictionary
Ω
ultraviolet The invisible part of the light spectrum whose rays have wavelengths shorter than the violet end of the visible spectrum and longer than X rays.
ultraviolet Of electromagnetic radiation beyond (higher in frequency than) light visible to the human eye.