umbra

n (pl -rae / -ri:; -ri/ or ~s) (astronomy 天) dark central part of the shadow cast by the earth or the moon in an eclipse, or of a sunspot 本影. Cf 参看 penumbra.

ulcerous, ulna, ulterior, ultimate, ultimately, ultimatum, ultimo, ultra violet, ultra-, ultramarine, ultrasonic, ultrasound, ultraviolet, ululate, ululation, Ulyanovsk, umber, umbilical, umbilical cord, umbilicus, umbrage, umbrella, umlaut, umpire, umpteen, umpteenth, un, un-, un-American, unabashed, unabated, unable, unabridged, unacceptable, unacceptably, unaccommodating, unaccompanied, unaccountable, unaccountably, unaccounted,