American English

Definition of index noun from the Oxford Advanced American Dictionary



    (pl. indexes or indices
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  1. 1In sense 4, indices is the only plural form. a list of names or topics that are referred to in a book, etc., usually arranged at the end of a book in alphabetical order or listed in a separate file or book Look it up in the index. Author and subject indexes are available on a library database.
  2. 2a system that shows the level of prices and pay, etc. so that they can be compared with those of a previous date the cost-of-living index The Dow Jones index fell 15 points this morning. stock-market indices housing cost indexes see also stock index
  3. 3a sign or measure that something else can be judged by The number of new houses being built is a good index of a country's prosperity.
  4. 4(mathematics) the small number written above a larger number to show how many times that number must be multiplied by itself. In the equation 42 = 16, the number 2 is an index.
See the Oxford Advanced Learner's Dictionary entry: index