"beyond the violet end of the visible spectrum," 1840, from ultra- "beyond" + violet. Ultra-red (1870) was a former name for what now is called infra-red.
an ultraviolet lamp
ultraviolet radiation
ultramontane
ultranationalism
ultrasonic
ultrasonography
ultrasound
ultraviolet
ululate
ululation
Ulysses
um
Umayyad
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