consumer price index (CPI) An index that represents the price of a market basket of goods that an urban family of four would purchase. By monitoring changes in the index over a period of time, changes in the price level and hence the inflation rate can be ascertained. Related Related Articles: Expanding How We Measure InflationWhat Our Cars Say About Us Ann Mills Share This Previous Articlebilateral aid Next Articlecreative destruction December 17, 2020