The term 'FORMAL YES' can be represented by two crossword solutions: IDO (3 letters) and ITISSO (6 letters). IDO is an acronym for the Latin phrase 'Id est, ' which translates to 'that is' and is used to confirm or agree with something. ITISSO is an acronym for the Latin phrase 'Ita est sic, ' which translates to 'YES, it is so' and is also used to confirm or agree with something. Both phrases are formal ways of saying 'YES' in Latin.