index

1 of 2

noun

in·​dex ˈin-ˌdeks 

plural indexes or indices ˈin-də-ˌsēz 

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

: thumb index

2

a

: a number (such as a ratio) derived from a series of observations and used as an indicator or measure

specifically : index number

b

: the ratio of one dimension of a thing (such as an anatomical structure) to another dimension

3

a

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

index

2 of 2

verb

indexed; indexing; indexes

transitive verb

1

a

: 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

indexer noun

Synonyms

Noun

• hand
• indicator
• needle
• pointer

Verb

• catalog
• catalogue
• enroll
• enrol
• enter
• inscribe
• list
• put down
• record
• register
• schedule
• slate

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 websites.

indexed all the books in the library by category

Recent Examples on the Web

Noun

Since then, according to the index, Musk’s net worth has dropped another $20 billion to about $170 billion. —Abigail Adams, Peoplemag, 19 Apr. 2024

The index is determined by the Labor Department's Bureau of Labor Statistics. —Susan Tompor, Detroit Free Press, 18 Apr. 2024

In the index’s forward-looking outlook rankings, tops among the 50 states were our directly competitive neighbors: Utah ranked 1st, Idaho 2nd and Arizona 3rd. —John Seiler, Orange County Register, 16 Apr. 2024

From their index of space-time-bending properties, the team extracted the elusive Druck term, publishing their estimate of the proton’s internal pressures in Nature in 2018. —Charlie Wood, WIRED, 14 Apr. 2024

If Glendale's numbers for these indices continue to far exceed We Energies' averages, the utility is obligated to address the issues, according to the agreement. —Claudia Levens, Journal Sentinel, 11 Apr. 2024

On an annual basis, the shelter index in the March CPI didn’t budge from the 5.7% rate seen a month before. —Alicia Wallace, CNN, 10 Apr. 2024

In stock markets abroad, indexes fell across much of Europe. —CBS News, 10 Apr. 2024

Markets reacted as expected to the hot inflation report on Wednesday, with all three major U.S. indexes falling more than 1%. —Bywill Daniel, Fortune, 10 Apr. 2024

Verb

Dune novelist Frank Herbert described this dialect in his books, but didn’t index it as fully as, say, J.R.R. Tolkien did with Elvish. —EW.com, 20 Feb. 2024

People-Search sites make your personal information easy to find It is estimated that there are over 300 million searches a day for personal names and information, accessed by billions of people-search websites indexed by Google. —Kurt Knutsson, Fox News, 29 Oct. 2023

The credit would be indexed to inflation, with adjustments made annually, and would carry income limits of $125,000 ($250,000 for joint filers) and an investment income limit of $20,000 ($40,000 for joint filers). —Andrew Leahey, Forbes, 1 Mar. 2024

Investors in 2022 had about $11.4 trillion in investments passively indexed to either the S&P 500 or in funds that use the index as a benchmark, according to S&P Global. —Aaron Gregg, Washington Post, 9 Feb. 2024

Among the fixes are raising vehicle registration fees or indexing gas taxes to inflation — the same approach Minnesota took. —Tribune News Service, Hartford Courant, 7 Jan. 2024

This process starts with the adoption of a modern IT setup in which data is de-siloed, meticulously indexed, and made visible so that advanced analytics can glean actionable insights at speed. —Fabrice Haiat, Forbes, 23 Feb. 2024

Google uses them to crawl and index the entire web for its search engine, which has become the interface to the web and brings the company billions of dollars a year. —Peter Rubin, Longreads, 15 Feb. 2024

The deal would index the child tax credit to inflation for the first time, so most parents would benefit from a boost of about $100 on their tax returns in 2025. —Jeff Stein, Washington Post, 1 Feb. 2024

Word History

Etymology

Noun

Latin indic-, index, from indicare to indicate

First Known Use

Noun

1561, in the meaning defined at sense 3a

Verb

1720, in the meaning defined at transitive sense 1a

Phrases Containing index

• body mass index
• card index
• cephalic index
• consumer price index
• cost-of-living index
• cranial index
• cross-index
• facial index
• glycemic index
• index card
• index case
• index finger
• index fossil
• index-linked
• index number
• index of refraction
• index patient
• misery index
• price index
• refractive index
• therapeutic index
• the retail price index
• thumb index
• viscosity index

Video

The True Story of the Backward Index

These people needed a computer

Kids Definition

index

1 of 2 noun

in·​dex ˈin-ˌdeks 

plural indexes

-ˌdek-səz

or indices -də-ˌsēz 

1

a

: a device (as the pointer on a scale) used to indicate a value or quantity

b

: something that leads a person to a particular fact or conclusion : indication

the price of goods is an index of the economy

2

: an alphabetical list in a printed work that gives with each item listed the page number where it may be found

3

plural usually indices : a mathematical figure, letter, or expression (as the exponent 3 in a³) showing a power or root of another

4

: a symbol ☞ used to direct attention

index

2 of 2 verb

1

a

: to provide with an index

index a book

b

: to list in an index

2

: to serve as an index of

indexer noun

Medical Definition

index

noun

in·​dex ˈin-ˌdeks 

plural indexes or indices -də-ˌsēz 

1

: index finger

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

3

a

: 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 juice

—Journal of the American Medical Association

b

: the ratio of one dimension of a thing (as an anatomical structure) to another dimension see cephalic index, cranial index

Legal Definition

index

1 of 2 noun

in·​dex

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

index

2 of 2 transitive verb

: to link (as wages, rates, or investments) to an index

under the contract wages were indexed to inflation