ultraviolet

a.紫外线的

ugly-looking, UHF, UHT, UK, ukulele, ulcer, ulcerate, ulceration, ulcerous, ulna, ulterior, ultimate, ultimately, ultimatum, ultimo, ultra violet, ultra-, ultramarine, ultrasonic, ultrasound, ululate, ululation, Ulyanovsk, umber, umbilical, umbilical cord, umbilicus, umbra, umbrage, umbrella, umlaut, umpire, umpteen, umpteenth, un, un-, un-American, unabashed, unabated, unable,