The term 'SAYS WHO?' is a rhetorical question used to challenge the validity of a statement or opinion. It is often used in response to an assertion that is seen as unfounded or unsubstantiated. The crossword solutions for this term are ASKS (4 letters) and ISTHATSO (8 letters). ASKS is a verb meaning to put a question to someone, while ISTHATSO is an expression of surprise or disbelief. Together, these two words capture the essence of the phrase 'SAYS WHO?', which is used to challenge the validity of a statement.