An instrument used in many states in place of a mortgage. A deed of trust is a document showing that a borrower conveys title to real property to a third party (trustee) to be held as security for a lender, with the provision that the trustee will return the title once the debt is paid. The trustee will sell the property and pay the debt if the borrower defaults. In other words, when you buy a house, a trustee will hold your Deed of Trust for your lender until you pay off your mortgage or default on the loan.