The term 'BORROW ON' can be broken down into three crossword solutions: MORTGAGE (8 letters), VERB (4 letters), and LOAN (4 letters). A MORTGAGE is a type of LOAN that is secured by real estate, such as a house. It is typically used to purchase a home and is paid back over a period of time with interest. A verb is an action word that describes an action, state, or occurrence. To borrow on something means to take out a LOAN against it. This could mean taking out a LOAN against a MORTGAGE, or taking out a LOAN against an asset such as a car or jewelry.