The term 'Mortgage Paper' is a legal document that is used to secure a loan. The document is also known as a DEED, which is a four-letter word that is often used in crossword puzzles. A mortgage paper is a written agreement between a borrower and a lender that outlines the terms of the loan, such as the amount of money borrowed, the interest rate, and the length of the loan. The document also serves as a record of the loan and can be used to enforce the terms of the loan if the borrower fails to make payments.