From Latin ultrā 'beyond' + violet, naming the invisible radiation discovered by Ritter in 1801 just past the violet end of the spectrum.
Relating to electromagnetic radiation with wavelengths shorter than visible violet light but longer than X-rays.
From Latin ultrā 'beyond' + English violet. Johann Wilhelm Ritter discovered ultraviolet radiation in 1801 by showing that invisible rays beyond violet light could darken silver chloride-treated paper. The term 'ultra-violet' was coined around 1840 to name these 'beyond-violet' rays. Key roots