Deficit Definition. A Deficit is a term used to describe an excess of liabilities over assets, of losses over profits, or of expenditures over income. In economics, it is commonly used to denote a negative balance of trade or payments. A Federal budget that spends more than it takes in is referred to as a Deficit budget. Conversely, if income exceeds payouts, then a surplus is the result. "Running a deficit" is sometimes proposed when a short term economic stimulus in the form of increased government spending is necessary to keep the economy stable until market growth returns. A Deficit is not to be confused with Debt. An annual deficit is the amount that will necessitate an increase the total amount of debt.