The term 'say so' can be broken down into five crossword solutions: Authority (9 letters), AVER (4 letters), Ifyou (5 letters), Voice (5 letters), and ASSENT (6 letters). Authority is the power to enforce rules or give orders, while AVER means to state or assert as a fact. Ifyou is an informal way of saying 'if you', and voice is the sound produced by the vocal folds. Finally, ASSENT is an agreement or approval. Together, these words form the phrase 'say so', which is used to express agreement or authority.