keenyoudaoicibaDictYouDict[keen 词源字典]
keen: [OE] The ancestral meaning of keen is ‘brave’. That is what its German and Dutch relatives, kühn and koen, mean, and that is what keen itself meant in the Old English period. But this sense had died out by the 17th century, having been replaced by the meanings familiar today, such as ‘eager’ and ‘sharp’.
[keen etymology, keen origin, 英语词源]
keen (adj.)youdaoicibaDictYouDict
c. 1200, from Old English cene "bold brave," later "clever, wise," from Proto-Germanic *kan- "be able to" (see can). Original prehistoric senses seem to have been both "brave" and "skilled;" cognate with Old Norse kænn "skillful, wise," Middle Dutch coene "bold," Dutch koen, Old High German kuon "pugnacious, strong," German kühn "bold, daring." Sense of "eager" is from mid-14c. The meaning "sharp" is peculiar to English: of blades and edges early 13c., of sounds c. 1400, of eyesight c. 1720. A popular word of approval in teenager and student slang from c. 1900.
keen (v.)youdaoicibaDictYouDict
"lament," 1811, from Irish caoinim "I weep, wail, lament," from Old Irish coinim "I wail." Related: Keened; keening. As a noun from 1830.