The term 'certify (to)' can be defined as to ATTEST or confirm something as true. The crossword solution for this term is 'ATTEST' which has 6 letters. Attesting is a process of providing evidence or testimony that something is true. It is often used in legal proceedings and documents, such as contracts, to ensure that all parties involved are aware of the facts and agree to them. Attesting can also be used in other contexts, such as when a person provides a statement or signature to verify the accuracy of a document or transaction.