TAD'%2C BIT (3 letters) The term TAD BIT is composed of two words, IOTA (4 letters) 'TAD' and BIT (3 letters). IOTA is a Greek letter that is the ninth letter in the Greek alphabet. It is also used to refer to a very small amount or quantity. BIT is an acronym for binary digit, which is the smallest unit of data in computing and digital communications. Together, the term TAD BIT refers to a very small amount or quantity of data.