Hastings' Dictionary of the Bible (1898)
JOT, Matt 5:18, or YOD (in Greek Iota). This is the name of the Hebrew letter i, which letter is the least of all the letters of the alphabet, being shaped not unlike our comma (,), and proverbially used by the Hebrews to signify the least thing imaginable; and hence the text expresses the idea that not the least requirement of the commandments of God shall in any wise be dispensed with; they shall all stand to the very letter.