sharpen (v.)youdaoicibaDictYouDict[sharpen 词源字典]
1520s, "bring to an edge or point," from sharp (adj.) + -en (1). Related: Sharpened; sharpening. Old English verb scearpian meant "to score, scarify;" also compare scearpung "scarifying." To sharpen (one's) pencil "prepare to get to work" is from 1957, American English.[sharpen etymology, sharpen origin, 英语词源]