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"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 (cf. Hebrew yodh).
iota i·o·ta (ī-ō'tə)
Symbol ι The ninth letter of the Greek alphabet.