The term kurofune (kanji: 黒船) means "black ships" in English. It is written くろふね in hiragana. It's pronounced roughly like "koo-row-foo-neh".
This refers historically to the ships (painted over with black tar) of the Portuguese traders of the 16th century, just before the start of isolationism in Japan, and to the U.S. naval ships led by Commodore Perry that arrived in 1853 and ended that period of isolationism. Remembering the one, the Japanese applied the word to the other.
Kurofune is used figuratively to refer to new products or concepts from foreign countries that exert a great influence in Japan.