an index of the changes in the prices of goods and services, based on the prices of the same goods and services at a period arbitrarily selected as a base, usually expressed as 100.
Origin
1885-90
Examples from the web for price index
So it is particularly instructive to look this week at our own commodity price index.
The search giant is working on its own price index based on online shopping.
We've adjusted all figures for inflation, using the consumer price index.
Tuition even outpaced a special price index deployed by colleges to help defend themselves against mounting criticism.