Jot

Easton's Bible Dictionary (1897)

Or Iota, the smallest letter of the Greek alphabet, used metaphorically or proverbially for the smallest thing (Matt. 5:18); or it may be = yod, which is the smallest of the Hebrew letters.

Smith's Bible Dictionary (1863)

the English form of the Greek iota, i.e., the smallest letter of the Greek alphabet. The Hebrew is yod, or y formed like a comma (’). It is used metaphorically to express the minutest thing.

Public domain dictionaries.