The term 'confirm the truth of' can be solved by three different crossword solutions: VERIFY (6 letters), VALIDATE (8 letters), and ATTEST (6 letters). VERIFY means to establish the truth or accuracy of something, usually through an examination or investigation. VALIDATE is similar to VERIFY, but it also implies that something is officially accepted as valid. ATTEST is to certify or affirm the truth of a statement or fact. All three words are used to confirm the truth of something.