An expression Jesus used in the Sermon on the Mount.
In Matthew 5:18 jot is a transliteration of the Greek letter iota. Originally, "jot" referred to the Hebrew letter yod, the smallest letter. Tittle comes from Middle English. It refers to the dot over abbreviated words. The King James Version translators used it for a Greek word meaning "little horn." Jews used the word to refer to the small markings that differentiate certain Hebrew letters. Jesus used both terms to stress the law's importance. He said not one jot or tittle would vanish from the law until all was fulfilled.