index
UK: ˈɪndɛks | US: ˈɪndɛks
n. 1. An alphabetical list of names, subjects, etc., with references to where they occur, typically at the end of a book.
n. 2. A numerical scale or indicator used to measure or compare things (e.g., economic index).
vt. 3. To record or list in an index.
The word index originates from Latin index (plural indices), meaning "forefinger, informer, or sign." It combines in- (toward) and -dex (from dicere, "to say/point"), reflecting the idea of "pointing toward" information. Over time, it evolved to denote lists or indicators that guide or reference data, retaining its core logic of directional indication.
The book's index helps readers locate specific topics quickly.
The stock market index reached a record high this year.
She indexed all the research papers by subject and author.
The library catalog is indexed digitally for easy access.
Inflation is often measured using a consumer price index.