a quantity whose variation over a period of time measures the change in some phenomenon.
Why Veterans Day And The Number 11 Are Tied TogetherNovember 11th is the 315th day of the year (except on leap years). It’s also Veterans Day, a federal holiday honoring all military veterans.
Origin of index number
First recorded in 1870–75
Also called index.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for index number
statistics a statistic indicating the relative change occurring in each successive period of time in the price, volume, or value of a commodity or in a general economic variable, such as the price level, national income, or gross output, with reference to a previous base period conventionally given the number 100
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012