The term 'MAKE VALID' can be broken down into two crossword solutions: 'AUTHENTICATE' (12 letters) and 'LEGALIZE' (8 letters). AUTHENTICATE means to prove the truth or accuracy of something, usually through evidence or documentation. LEGALIZE means to make something legal or acceptable according to the law. Together, these two words suggest that something must be proven to be true and then accepted by the law in order to be considered valid.