Meaning

noun radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays

adjective having or employing wavelengths shorter than light but longer than X-rays; lying outside the visible spectrum at its violet end

originEtymology tree Proto-Indo-European *h₂el- Latin ūls Proto-Indo-European *-teros? Latin -ter Old Latin -ād Latin -ā Latin ultrābor. English ultra- Latin viola Old French -ette Old French violettebor. Middle English violet English violet English ultraviolet From ultra- (“beyond”) + violet (“violet”).

Etymology from Wiktionary, CC BY-SA 3.0