What is the term for a sustained increase in the aggregate price level?

 Recession - In economics, a recession is a business cycle contraction that occurs when there is a general decline in economic activity. Recessions generally occur when there is a widespread drop in spending.

Stagflation - Stagflation is an economic cycle characterized by slow growth and a high unemployment rate accompanied by inflation. Economic policymakers find this combination particularly difficult to handle, as attempting to correct one of the factors can exacerbate another.

Depression - An economic depression is a period of carried long-term economic dow that is the result of lowered economic activity in one major or more national economies.

Inflation - In economics, inflation is a general increase of the prices. This is usually measured using the consumer price index (CPI). When the general price level rises, each unit of currency buys fewer goods and services; consequently, inflation corresponds to a reduction in the purchasing power of money.