Jot, n.
Etymology: [L. iota, Gr. i. Heb. y), the smallest letter of the Greek alphabet. Cf. Iota.]
An iota; a point; a tittle; the smallest particle. Cf. Bit, n. Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. Matt. v. 18. Neither will they bate One jot of ceremony. Shak.
1 other Webster entry under this spelling
Jot, v. t. [imp. & p. p. Jotted; p. pr. & vb. n. Jotting.]
To set down; to make a brief note of; -- usually followed by down.
Shades of meaning
Fernald has no entry of its own for jot; he lists it under particle.
He lists it without comment; the entries above explain its neighbors.