ultraviolet
adj.
"beyond the violet end of the visible spectrum," 1840, from ultra- + violet. Ultra-red (1870) was a former name for what now is called infra-red.
〔李〕[ultra-=beyond在⋯以外的；violet n.紫色 →“be-yond the violet在紫色之外的”→] a.lying beyond the violet end of the visible spectrum紫外的