U-boat

n (esp in World War II) Germansubmarine （尤指第二次世界大战中的）德国潜艇.

typically, typify, typist, typo, typo-graphically, typographer, typographical, typography, tyrannical, tyrannically, tyrannize, tyrannise, tyranny, tyrant, tyrany, tyre, tyre (US tire), tyro, tzar, U, U, u, U-turn, UAE, UAR, ubiquitous, ubiquity, UCCA, UDA, udder, UDI, UDR, UEFA, UFO (also ufo), ugh, ugli, ugliest, ugliness, ugly, ugly-looking, UHF, UHT,