Negative Amortization - A loan payment schedule in which the outstanding principal balance of a loan goes up rather than down because the payments do not cover the full amount of interest due. The monthly shortfall in payment is added to the unpaid principal balance of the loan.

Non-Assumption Clause - A statement in a mortgage contract forbidding the assumption of the mortgage by another borrower without the prior approval of the lender.

Notice of Default - Written notice to a borrower that a default has occurred and that legal action may be taken.