index

Concise Oxford English Dictionary © 2008 Oxford University Press:
index /ˈɪndɛks/

▶noun (pl. indexes or especially in technical use indices /ˈɪndɪsiːz/)

• 1 an alphabetical list of names, subjects, etc., with references to the places in a book where they occur.

  ■ an alphabetical list or catalogue of books or documents.

• 2 an indicator, sign, or measure of something.

  ■ a number representing the relative value or magnitude of something in terms of a standard: a price index.

• 3 Mathematics an exponent or other superscript or subscript number appended to a quantity.

• 4 Printing a symbol shaped like a pointing hand used to draw attention to a note.

▶verb

• 1 record in or provide with an index.

• 2 link the value of (prices, wages, etc.) automatically to the value of a price index.

• 3 (often as noun indexing) (of a machine or part) move from one predetermined position to another to carry out a sequence of operations.

– derivatives
indexable adjective,
indexation noun,
indexer noun,
indexible adjective.

– origin ME: from L. index, indic- ‘forefinger, informer, sign’, from in- ‘towards’ + a second element rel. to dicere ‘say’ or dicare ‘make known’; cf. indicate.