What is the definition of the term Consumer Price Index?

Consumer Price Index (CPI) is a measure of changes in the purchasing-power of a currency and the rate of inflation. The consumer price index expresses the current prices of a basket of goods and services in terms of the prices during the same period in a previous year, to show effect of inflation on purchasing power. It is one of the best known lagging indicators. See also producer price index.Refer to link below.