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

Noah Webster's New International Dictionary of the English Language

1. (n.) An iota; a point; a tittle; the smallest particle. Cf. Bit, n.

2. (v. t.) To set down; to make a brief note of; -- usually followed by down.