a numerical scale used to compare variables with one another or with some reference number
"The economic index showed that inflation had risen significantly compared to last year's baseline figure."
a number or ratio (a value on a scale of measurement) derived from a series of observed facts; can reveal relative changes as a function of time
"The economic index showed a steady decline over the last quarter, signaling worsening conditions for small business owners."
an alphabetical listing of names and topics along with page numbers where they are discussed
"I flipped to the back of the cookbook to find the recipe for lasagna under the index before starting dinner."
the finger next to the thumb
"He tapped his index finger on the table to get everyone's attention before starting the meeting."
An alphabetical listing of items and their location.
"I flipped to the back of the cookbook to find the recipe in the index under "chicken.""
In plain English: An index is a list at the back of a book that helps you find specific topics quickly.
"She used her finger to trace the index on the book's spine to find the right page."
Usage: Use "index" to refer to an alphabetical list at the back of a book that points readers to where specific topics are discussed. Do not use it interchangeably with "indicate," as the noun specifically denotes the reference tool itself rather than the action of pointing something out.
list in an index
"I added all the relevant sources to the end of my paper and created a detailed index so readers could easily find them."
To arrange an index for something, especially a long text.
"The editor spent weeks creating a detailed index to help readers quickly locate topics in the thousand-page legal treatise."
In plain English: To index something means to organize it into a list so you can find it easily later.
"You should index your research papers to make them easier to find later."
Usage: Do not use "index" as a general synonym for listing or cataloging items; instead, reserve it specifically for creating a reference list of terms and their locations within a book or document. You should only say you are indexing a text when you are compiling those specific cross-references to help readers find information quickly.
An unincorporated community in Miller County, Arkansas.
"Residents of Index often drive south to Rogers for their weekly shopping trips."
The word "index" comes from the Latin index, which originally meant a discoverer or informer as well as something that points to or indicates other things. It entered English via the verb indicō, meaning "to point out" or "to show."