index

[ in-deks ]

noun

, plural in·dex·es, in·di·ces [in, -d, uh, -seez].

1. (in a nonfiction book, monograph, etc.) a more or less detailed alphabetical listing of names, places, and topics along with the numbers of the pages on which they are mentioned or discussed, usually included in or constituting the back matter.
2. a sequential arrangement of material, especially in alphabetical or numerical order.
3. something used or serving to point out; a sign, token, or indication:

   a true index of his character.

4. something that directs attention to some fact, condition, etc.; a guiding principle.
5. a pointer or indicator in a scientific instrument.
6. a piece of wood, metal, or the like, serving as a pointer or indicator.
7. Digital Technology.
   1. a value that identifies and is used to locate a particular element within a data array or table.
   2. a reference table that contains the keys or references needed to address data items.
   3. the part of a search engine where website addresses are cataloged with their associated keywords in order to quickly retrieve the most relevant web pages when a user submits a search query.
8. Also called fist, hand. Printing. a sign in the shape of a hand with extended index finger, used to point out a particular note, paragraph, etc.
9. a light, smooth cardboard stock.
10. the forefinger.
11. a number or formula expressing some property, ratio, etc., of something indicated:

    index of growth; index of intelligence.

12. Statistics. index number.
13. Economics. price index.
14. Algebra.
    1. an exponent.
    2. the integer n in a radical  defining the n- th root: ∛ is a radical having index three.
    3. a subscript or superscript indicating the position of an object in a series of similar objects, as the subscripts 1, 2, and 3 in the series x 1 , x 2 , x 3 .
    4. winding number.
15. Horology. a leverlike regulator for a hairspring.
16. (initial capital letter) Roman Catholic Church.
    1. Index Librorum Prohibitorum.
    2. Index Expurgatorius.
17. (usually initial capital letter) any list of forbidden or otherwise restricted material deemed morally or politically harmful by authorities:

    an Index of disapproved books relating to Communism.

18. Optics. index of refraction.
19. Obsolete.
    1. a table of contents.
    2. a preface or prologue.

verb (used with object)

1. to provide with an index, as a book.
2. to enter in an index, as a name or topic.
3. to serve to indicate:

   warm breezes indexing the approach of spring.

4. to place (a book) on an official list as politically or morally harmful:

   The commissar insisted on indexing the book.

5. to rotate (work) on a milling machine in order to repeat the milling operation at a new position.
6. Economics. to adjust (wages, taxes, etc.) automatically according to changes in the cost-of-living level or another economic indicator, especially to offset inflation.
7. Digital Technology. (of a search engine) to catalog (a website) using keywords:

   Search engines use automated algorithms to index billions of web pages, but that still accounts for only a fraction of the content on the internet.

index

/ ˈɪndɛks /

noun

1. an alphabetical list of persons, places, subjects, etc, mentioned in the text of a printed work, usually at the back, and indicating where in the work they are referred to
2. See thumb index
3. library science a systematic list of book titles or author's names, giving cross-references and the location of each book; catalogue
4. an indication, sign, or token
5. a pointer, needle, or other indicator, as on an instrument
6. maths
   1. another name for exponent
   2. a number or variable placed as a superscript to the left of a radical sign indicating by its value the root to be extracted, as in ³√8 = 2
   3. a subscript or superscript to the right of a variable to express a set of variables, as in using x i for x 1 , x 2 , x 3 , etc
7. a numerical scale by means of which variables, such as levels of the cost of living, can be compared with each other or with some base number
8. a number or ratio indicating a specific characteristic, property, etc

   refractive index

9. Also calledfist a printer's mark ( ) used to indicate notes, paragraphs, etc
10. obsolete.
    a table of contents or preface

verb

1. to put an index in (a book)
2. to enter (a word, item, etc) in an index
3. to point out; indicate
4. to index-link
5. to move (a machine or a workpiece held in a machine tool) so that one particular operation will be repeated at certain defined intervals

index

1. An alphabetical list of subjects treated in a book. It usually appears at the end of the book and identifies page numbers on which information about each subject appears.

Derived Forms

• ˈindexless, adjective
• ˈindexer, noun

Other Words From

• index·a·ble adjective
• index·er noun
• in·dexi·cal adjective
• in·dexi·cal·ly adverb
• index·less adjective
• non·indexed adjective
• over·index verb (used with object)
• over·index·ing noun
• re·index verb (used with object)
• un·indexed adjective
• well-indexed adjective

Word History and Origins

Origin of index¹

First recorded in 1350–1400; Middle English, from Latin: “informer, pointer,” equivalent to in- in- ² + -dec- (combining form of dic-, “show, declare, indicate,” akin to teach; indicate ) + -s nominative singular ending;

Word History and Origins

Origin of index¹

C16: from Latin: pointer, hence forefinger, title, index, from indicāre to disclose, show; see indicate

Example Sentences

The three major stock indexes in the US are on track to end the day lower, after rising roughly 5% since 4 November, the day before the election.

From BBC

Although the government denied any wrongdoing, many of India’s top academics, rights activists and popular opposition leaders found themselves in jail and the country kept sliding on the global press freedom index.

From BBC

Trump’s broader agenda of cutting taxes and regulations and bolstering domestic economic growth also triggered a buying spree across stocks, with the Standard & Poor’s 500 index hitting a record last week.

From Los Angeles Times

According to the NHS, the index measures what is a healthy weight for your height, and would have put Mrs Savage at the very start of the obese range, which runs from 30 to 30.9.

From BBC

Major stock indexes, the dollar and US bonds have all made gains in recent days.

From BBC

What Is The Plural Of Index?

Plural word for index

The plural form of index is either indices, pronounced [ in-duh-seez ], or indexes. Indices is more widely used. The plurals of several other singular words that end in -ex or -ix are also formed this way, including appendix/appendices, cortex/cortices, and codex/codices. 

Irregular plurals that are formed like indices derive directly from their original pluralization in Latin. However, the standard English plural -es is often also acceptable for these terms, as in appendixes.