The term THREE TRIOS refers to three groups of three, and can be represented by the crossword solutions NONET (5 letters), NINE (4 letters), and ENNEAD (6 letters). NONET is derived from the Latin phrase 'nōnus-nōna, ' which means NINE each, and is used to refer to a group of NINE. NINE is simply the number NINE, and is used to refer to a group of NINE. ENNEAD is derived from the Greek phrase 'ennea, ' which means NINE, and is also used to refer to a group of NINE. Therefore, the term THREE TRIOS can be used to refer to three groups of NINE.