Definition of index number in English:

index number

noun

  • 1A number showing the variation in a price or value compared with the price or value at a specified earlier time (often represented by the number 100)

    ‘the official index numbers of agricultural production show declining production’
    1. 1.1 A number giving the magnitude of a physical property or other measured phenomenon in terms of a standard.
      ‘foods are assigned an index number from 1 to 100 (100 being pure glucose)’