建國一百年，百年紀念日，英語是：centennial，突然想知道這字的字源是什麼?
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centennial (adj.) 
c.1797, formed in English from L. centum "one hundred" (see hundred) + ending from biennial. First used as a noun in 1876.bicentennial also, in 19c., bi-centennial; 1843 (adj.), 1871 (noun), Amer.Eng., from bi- + centennial (q.v.). In rivalry with bicentenary (1831) which seems to have been the more common word in Britain.sesquicentennial "pertaining to a century and a half," 1880, from L. sesqui- "one and a half" (from semis "a half" + -que "and") + centennial (q.v.). First recorded ref. is to Baltimore’s.輸入cent
cent late 14c., from L. centum "hundred" (see hundred). M.E. meaning was "one hundred," but shifted 17c. to "hundredth part" under influence of percent. Chosen in this sense in 1786 as name for U.S. currency unit by Continental Congress. The name was first suggested by Robert Morris in 1782 under a different currency plan. Before the cent, colonial dollars were reckoned in ninetieths, based on the exchange rate of Pennsylvania money and Spanish coin.