index
n. countablen. an alphabetical list of names or topics at the end of a book that tells you which page to find them on. It can also be a number that shows how much something, like a price, has changed.
n. an alphabetical list of subjects with references to their locations in a text; alternatively, a statistical measure used to track changes in a specific data set over time.
I looked in the index to find the chapter on history.
The consumer price index serves as a primary indicator for measuring inflation and adjusting social security benefits.
While the back-of-the-book index remains essential for academic research, digital search functions have largely replaced it for casual readers seeking specific keywords within a text.
From Latin index (“a discoverer, informer, spy; of things, an indicator, the forefinger, a title, superscription”), from indicō (“point out, show”); see indicate.
The plural form is usually 'indexes' for books and 'indices' in technical, mathematical, or economic contexts.
I found the word in the index of page 50I found the word in the index on page 50When referring to the location within the book where the index itself is found, use 'on'; when referring to the entry inside the index, use 'in'.