The crossword solution for the term 'AFFIX SECURELY' is 'PASTEDOWN, ' which is a nine-letter word. Pastedown is a noun that refers to the process of affixing something securely with an adhesive. It is commonly used in bookbinding, where the endpapers are glued to the inside covers of a book. Pastedown is also used to refer to the adhesive strips used to attach photographs or other items to a surface.