A price index is a measure of the average level of prices of goods and services in an economy over a specified period. Synonyms for price index include cost of living index, inflation gauge, consumer price index, and price level index. The cost of living index measures changes in the cost of goods and services essential for an average household, while the inflation gauge measures changes in the general price level in an economy. The consumer price index measures changes in the prices of goods and services bought by consumers, while the price level index measures the average level of prices of goods and services in an economy. These price indexes are used to track inflation, measure purchasing power, and adjust wages and prices in an economy.