# index

noun
in·​dex | \ ˈin-ˌdeks \
plural indexes or indices\ ˈin-​də-​ˌsēz \

## Definition of index

(Entry 1 of 2)

1 : a list (as of bibliographical information or citations to a body of literature) arranged usually in alphabetical order of some specified datum (such as author, subject, or keyword): such as
a : a list of items (such as topics or names) treated in a printed work that gives for each item the page number where it may be found
b : a list of publicly traded companies and their stock prices
c : a bibliographical analysis of groups of publications that is usually published periodically
d
2a : a number (such as a ratio) derived from a series of observations and used as an indicator or measure specifically
b : the ratio of one dimension of a thing (such as an anatomical structure) to another dimension
3a : a device (such as the pointer on a scale or the gnomon of a sundial) that serves to indicate a value or quantity
b : something (such as a physical feature or a mode of expression) that leads one to a particular fact or conclusion : indication
4 plural usually indices : a number or symbol or expression (such as an exponent) associated with another to indicate a mathematical operation to be performed or to indicate use or position in an arrangement 3 is the index of the expression {latex}\sqrt[3]{5}{/latex} to indicate the cube root of 5
5 : a character ☞ used to direct attention to a note or paragraph

called also fist

6 : a list of restricted or prohibited material specifically, capitalized : a formerly published list of books the reading of which was prohibited or restricted for Roman Catholics by the church authorities

index

verb
indexed; indexing; indexes

Definition of index (Entry 2 of 2)

transitive verb

1a : to provide with an index
b : to list in an index all persons and places mentioned are carefully indexed
2 : to serve as an index of
3 : to regulate (wages, prices, interest rates, etc.) by indexation

intransitive verb

: to index something

Keep scrolling for more

Verb

indexer noun

Synonyms: Noun

Synonyms: Verb

## Examples of index in a Sentence

Noun Look up the recipe for potato soup in the index. Potato soup is listed under “soup” in the index. The card catalog is an index to the materials in the library. the index on a scale Verb This search engine has indexed hundreds of millions of Web sites. indexed all the books in the library by category
Recent Examples on the Web: Noun In comparison, the broader NASDAQ index is up by 2% year-to-date. On Monday, the index well was at 655.7 feet, down 0.2-foot from Sunday, according to the EAA. In comparison, the S&P 500 index was at 390 in March 1991 versus 4019 now. But in 2015 testimony to California regulators, a utility meteorologist said the index was too volatile and can generate false positives. The benchmark index is on track for its second straight weekly decline. The index is slightly different than just looking at median prices. The index is up 19% YTD, and Morgan Stanley, for one, thinks the rally is due for a pause. The tech-heavy index was on track to close in a correction, or down more than 10% from its Feb. 12 record. Recent Examples on the Web: Verb Several Republicans on Thursday announced their support for a plan by GOP Sens. Tom Cotton of Arkansas and Mitt Romney of Utah that would raise the minimum wage by a smaller amount more slowly and thereafter index it to inflation. Finally, the last Smart Scan task will re-index a Mac’s Spotlight database as well as rebuilding the mail search database. The bill would also index the minimum wage to inflation after reaching $15 an hour in 2025. On Tuesday, Republican Sens. Tom Cotton of Arkansas and Mitt Romney of Utah introduced a counterproposal to raise the minimum wage to$10 by 2025 and then index the wage to inflation every two years. One option would be to index a minimum wage increase to the cost of living in each state instead of mandating an across-the-board rate. Search bots typically scan websites in order to rank and index them for search engine results. The president’s centerpiece proposal is to index the drug prices paid by Medicare to lower prices paid by foreign countries. Late last year, Google launched a facial recognition service limited to celebrities that is aimed primarily at companies that need to search or index large collections of entertainment video.

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'index.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

## First Known Use of index

Noun

1561, in the meaning defined at sense 3a

Verb

1720, in the meaning defined at transitive sense 1a

## History and Etymology for index

Noun

Latin indic-, index, from indicare to indicate

Keep scrolling for more

## Learn More about index

Share index

Time Traveler for index

## The first known use of index was in 1561

See more words from the same year

## Statistics for index

Last Updated

10 Apr 2021

Cite this Entry

“Index.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/index. Accessed 21 Apr. 2021.

Style: MLA
MLA Chicago APA Merriam-Webster

Keep scrolling for more

More Definitions for index

index

noun

## English Language Learners Definition of index

(Entry 1 of 2)

: an alphabetical list at the end of a book that shows the page where each thing in the list can be found
: a group of related things that are in alphabetical or numerical order
: a sign or number that shows how something is changing or performing : a number that indicates changes in the level of something (such as a stock market) when it rises or falls

index

verb

English Language Learners Definition of index (Entry 2 of 2)

: to provide an index for (something, such as a book)
: to list or include (something) in an index
: to link wages, benefits, etc., to a measurement of changes in the price of goods and services so that they increase at the same rate

index

noun
in·​dex | \ ˈin-ˌdeks \
plural indexes or indices\ ˈin-​də-​ˌsēz \

## Kids Definition of index

(Entry 1 of 2)

1 : a list of names or topics (as in a book) given in alphabetical order and showing where each is to be found
2 : pointer sense 1 the index on a scale
3 : sign entry 1 sense 3, indication Prices are an index of business conditions.

index

verb
indexed; indexing

Kids Definition of index (Entry 2 of 2)

1 : to provide (as a book) with an index
2 : to list in an index The topics are indexed.

index

noun
in·​dex | \ ˈin-ˌdeks \
plural indexes or indices\ -​də-​ˌsēz \

## Medical Definition of index

1
2 : a list (as of bibliographical information or citations to a body of literature) arranged usually in alphabetical order of some specified datum (as author, subject, or keyword) Index Medicus of the United States National Library of Medicine
3a : a ratio or other number derived from a series of observations and used as an indicator or measure (as of a condition, property, or phenomenon) physiochemical indexes of the urine, the blood, and the gastric juiceJournal of the American Medical Association
b : the ratio of one dimension of a thing (as an anatomical structure) to another dimension

Keep scrolling for more

index

noun
in·​dex

## Legal Definition of index

(Entry 1 of 2)

: a numerical measure or indicator (as of inflation or economic performance) — see also consumer price index

Legal Definition of index (Entry 2 of 2)

: to link (as wages, rates, or investments) to an index under the contract wages were indexed to inflation

Keep scrolling for more

More from Merriam-Webster on index

Thesaurus: All synonyms and antonyms for index

Britannica English: Translation of index for Arabic Speakers

Britannica.com: Encyclopedia article about index

Comments on index

What made you want to look up index? Please tell us where you read or heard it (including the quote, if possible).

#### Test Your Vocabulary

Name that Thing: Flower Edition

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ

Anagram puzzles meet word search.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play
Ask the Editors
Word Games