iota (n.)youdaoicibaDictYouDict[iota 词源字典]
"very small amount," 1630s, figurative use of iota, ninth and smallest letter in the Greek alphabet. Modern use is after Matt. v:18 (see jot), but iota in classical Greek also was proverbially used of anything very small. The letter name is from Semitic (compare Hebrew yodh).[iota etymology, iota origin, 英语词源]