ultimatum

n (pl ~s or -ta / -tE; -tE/) final demand or statement of terms to be accepted without discussion, eg one sent to a foreign government and threatening war if the conditions are not accepted 最後通牒; 哀的美敦书: accept, reject, issue, deliver an ultimatum 接受、 拒绝、 发出、 送交最後通牒.

UEFA, UFO (also ufo), ugh, ugli, ugliest, ugliness, ugly, ugly-looking, UHF, UHT, UK, ukulele, ulcer, ulcerate, ulceration, ulcerous, ulna, ulterior, ultimate, ultimately, ultimo, ultra violet, ultra-, ultramarine, ultrasonic, ultrasound, ultraviolet, ululate, ululation, Ulyanovsk, umber, umbilical, umbilical cord, umbilicus, umbra, umbrage, umbrella, umlaut, umpire, umpteen,