rivulet (n.)youdaoicibaDictYouDict[rivulet 词源字典]
1580s, from Italian rivoletto, diminutive of rivolo, itself a diminutive of rivo "brook," from Latin rivus "stream, brook," from PIE *reiwos, literally "that which flows," from root *reie- "to flow, run" (see Rhine). For ending, see -let.[rivulet etymology, rivulet origin, 英语词源]