Learn That Word

Synonyms for Ultraviolet (same or very similar meaning)

WordNet sense 1 (radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays):
UV, ultraviolet illumination, ultraviolet light, ultraviolet radiation

WordNet sense 2 (impossible or nearly impossible to see; imperceptible by the eye):
invisible, unseeable

From the ODE community, based on WordNetadd/edit