英语词源字典 - 在线词源网站

cost (n.): c. 1200, from Old French cost (12c., Modern French coût) "cost, outlay, expenditure; hardship, trouble," from Vulgar Latin *costare, from Latin constare, literally "to stand at" (or with), with a wide range of figurative senses including "to cost." The idiom is the same one used in Modern English when someone says something "stands at X dollars" to mean it sells for X dollars. The Latin word is from com- "with" (see com-) + stare "to stand," from PIE root *sta- "to stand" (see stet).
fed (adj.): past participle adjective from feed (v.). Fed up "surfeited, disgusted, bored," is British slang first recorded 1900 (some early uses connect it to the Boer War), extended to U.S. by World War I; probably from earlier phrases like fed up to the back teeth. Earlier it was used of livestock, "fatten up by feeding." The notion probably is the same one in to have had enough "to have had too much."
G-man (n.): "FBI agent," 1930, shortening of government man; used earlier in an Irish context (1917), but the abbreviation is perhaps the same one.
guest-room (n.): also guestroom, 1630s, from guest (n.) + room (n.). Guest chamber is recorded from 1520s. Old English had giestærn "guest-chamber," with the second element the same one as in barn.
undertake (v.): c. 1200, "to entrap;" c. 1300, "to set about (to do)," from under + take (v.). Similar formation in French entreprendre "to undertake," from entre "between, among" + prendre "to take." The under in this word may be the same one that also may form the first element of understand. Old English had underniman "to trap, accept" (cognate with Dutch ondernemen, German unternehmen).