1) the Hebrew letter `, the smallest of them all
1a) hence equivalent to the minutest part
Part of Speech: noun neuter
Of Hebrew origin (the tenth letter of the Hebrew alphabet); "iota", the name of the eighth letter of the Greek alphabet, put (figuratively) for a very small part of anything: - jot.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root ἰῶτα; click on the second column to search for that grammatical form of the root ἰῶτα; click on the third column to search for that word and grammatical form; click on the total to search for the root ἰῶτα.