index

1 of 2

noun

in·​dex ˈin-ˌdeks How to pronounce index (audio)
plural indexes or indices ˈin-də-ˌsēz How to pronounce index (audio)
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
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

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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Noun
The geomagnetic activity has a Kp index of 5, meaning the northern lights will also be brighter, according to NOAA. Eric Lagatta, USA TODAY, 27 Nov. 2024 Separately, Palantir was also recently included in the S&P 500 index and this could also be boosting visibility for the stock while broadening its appeal to institutional investors. Trefis Team, Forbes, 27 Nov. 2024
Verb
Experts suggest that battery drain after a major update is normal because of background processes like indexing and recalibrating the battery. Tom Rogers, Newsweek, 26 Nov. 2024 Some experts would prefer to see income tax thresholds that apply to Social Security benefits indexed for inflation so that people could earn more in retirement without facing a tax hit. Susan Tompor, Detroit Free Press, 14 Nov. 2024 See all Example Sentences for index 

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

Time Traveler
The first known use of index was in 1561

Dictionary Entries Near index

Cite this Entry

“Index.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/index. Accessed 3 Dec. 2024.

Kids Definition

index

1 of 2 noun
in·​dex ˈin-ˌdeks How to pronounce index (audio)
plural indexes
-ˌdek-səz
or indices -də-ˌsēz How to pronounce index (audio)
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 How to pronounce index (audio)
plural indexes or indices -də-ˌsēz How to pronounce index (audio)
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
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 juiceThe 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

More from Merriam-Webster on index

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