Iota (upper case Ι, lower case ι) is the 9th letter of the Greek alphabet. In the system of Greek numerals it has a value of 10.
Iota is the smallest letter in the Greek alphabet.
The word iota is also used in English to express a very small amount. By some accounts this usage stems from the third- and fourth-century theological dispute over the Arian doctrine that Jesus and God the Father were of distinct but similar substances—Greek homoi-ousios—against the orthodox doctrine that they are one substance—Greek homo-ousios. The two words differ by one iota.
