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
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
indexed; indexing; indexes
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
: to index something
indexer
noun
Synonyms
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
Rocio Fabbro, Quartz, 14 Nov. 2024
Its average index score for 2024 is 79.0, putting it among the 125 most difficult markets.
—Jasmine Cui, NBC News, 10 Nov. 2024
Jim Cramer, CNBC, 4 Nov. 2024
One of the similarities between the Canadian tax system and the U.S. tax system is that most income tax and benefit amounts in both countries are indexed to inflation (only a few countries adjust their income tax thresholds for inflation—out of 160 economies, 131 have no adjustment at all).
—Kelly Phillips Erb, Forbes, 2 Nov. 2024
See all Example Sentences for index 
Examples are automatically compiled from online sources to
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Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Noun
Major stock indexes, including the Dow Jones Industrial Average, the S&P 500, and the Nasdaq, all hit record highs in the days following Trump’s election win.
—Rocio Fabbro, Quartz, 14 Nov. 2024
Its average index score for 2024 is 79.0, putting it among the 125 most difficult markets.
—Jasmine Cui, NBC News, 10 Nov. 2024
Verb
Virtually no money is indexed to Club name Nvidia but shares were up 2% in the premarket after S & P Dow Jones Indices announced late Friday that the chipmaker would replace rival Intel in the 30-stock Dow.
—Jim Cramer, CNBC, 4 Nov. 2024
One of the similarities between the Canadian tax system and the U.S. tax system is that most income tax and benefit amounts in both countries are indexed to inflation (only a few countries adjust their income tax thresholds for inflation—out of 160 economies, 131 have no adjustment at all).
—Kelly Phillips Erb, Forbes, 2 Nov. 2024
See all Example Sentences for index
Articles Related to index
Video
The True Story of the Backward Index
These people needed a computer
Dictionary Entries Near index
Cite this Entry
“Index.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/index. Accessed 22 Nov. 2024.
Copy CitationKids 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 verb1
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
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—The Journal of the American Medical Association
The 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
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