late 14c. metathesis of thritti, from Old English tritig, from tri, treo "three" (see three) + -tig "group of ten" (see -ty (1)). Similar formation in Old Frisian thritich, Old Saxon thritig, Dutch dertig, Old High German drizzug, German dreissig.
The Thirty Years' War (1842) was a religious power struggle waged 1618-48, mainly on German soil. The symbol -30- as printer and telegrapher's code to indicate the last sheet or line of copy or a dispatch is recorded from 1895. In 20c. jargon of newspaper journalism, it came to be a traditional sign-off signal and slang word for "the end."
例文
1. By 1973 the government deficit equaled thirty per cent of GNP.
1973年まで、政府の財政赤字は国民総生産の30%に相当した。
2.I know that you 'vebeen studying chimpanzees for thirty years now.
あなたがチンパンジーを研究してから30年になることを知っています。
3. Thirty seconds later she reappeared and beckoned them forward.
30秒後に彼女はまた現れ、彼らが前に来ることを合図した。
4.The price of a single ticket is thirty -nine pounds.
片道切符の価格は39ポンドです。
5.They walked through the dense Mozambican bush for thirty six hours.