index

A numerical scale indicating changes in value, price, or performance.

"The stock market index fell sharply."

An alphabetical list of names or subjects, usually at the back of a book.

"Look up the topic in the index."

To create an alphabetical list of names or subjects for a book.

"The researcher indexed all her sources."

To link or adjust prices, wages, or values to an existing index.

"Salaries are often indexed to inflation."