/
ˈɪndɛks/
n.
 (pl. indexes or especially in technical use indices  
/ˈɪndɪsiːz/
)
    - 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. 
- 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. 
- Mathematics  an exponent or other superscript or subscript number appended to a quantity.
- Printing  a symbol shaped like a pointing hand used to draw attention to a note.
v.
   - record in or provide with an index.
- link the value of (prices, wages, etc.) automatically to the value of a price index.
- 
[often as noun indexing]
 (of a machine or part) move from one predetermined position to another to carry out a sequence of operations.
Derivative
- indexable adj.
- indexation n.
- indexer n.
- indexible adj.
Etymology
ME: from L. index, indic- ‘forefinger, informer, sign’, from in- ‘towards’ + a second element rel. to dicere ‘say’ or dicare ‘make known’; cf. indicate.