Definitions:
(in a book or set of books) an alphabetical list of names, subjects, etc. with reference to the pages on which they are mentioned

a sign or measure of something

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

a pointer on an instrument, showing a quantity, a position on a scale, etc.

record (names, subjects, etc.) in an index

link the value of (prices, wages, or other payments) automatically to the value of a price index

(of a machine or part of one) move from one predetermined position to another in order to carry out a sequence of operations