Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
Jot
Or Iota, the smallest letter of the Greek alphabet, used metaphorically or proverbially for the smallest thing (Mt. 5:18); or it may be = yod, which is the smallest of the Hebrew letters.
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.