an index

Meanings

1. 1phrasecountable

   An alphabetical list at the back of a book showing where topics appear.

   Grammar: Countable: you can say one index, two indexes; it usually comes after the noun "book" or "report".

   Patterns

   • an index of something
   • in the index
   • look something up in an index

   Turn to the back of the book and check an index to find the chapter on volcanoes.

   An index at the end of the report lists every chart and table.

   If a name is not in an index, the reader may never find that page.

2. 2phrasecountablefinancebusiness

   A number that shows how prices, wages, or values change over time compared with a fixed starting point.

   Grammar: Countable; often followed by "of" plus what is being measured, as in "an index of consumer prices".

   Patterns

   • an index of something
   • rise in an index
   • fall in an index

   Economists watch an index of retail prices to judge how fast the cost of living is rising.

   The housing index climbed three points last month.

   Investors use an index of the largest companies to compare fund performance.

3. 3phrasecountableformal

   A sign or measure that shows how strong or serious something is.

   Grammar: Countable and usually followed by "of": an index of how healthy a society is.

   Patterns

   • an index of something
   • be an index of something

   Reading scores are often treated as an index of how well a school is doing.

   For historians, the size of a city's market can be an index of its wealth.

   A rising crime rate is only one index of social trouble.

Common combinations

the index of a book

She flipped to the index of the book to find the map.

a price index

The government publishes a price index every month.

an index of something

Test results are an index of student progress.

look something up in the index

Look the term up in the index at the back.

rise in the index

Share prices showed a sharp rise in the index.

Synonyms and how they differ

contents

Use "contents" for the list at the front of a book that follows the order of chapters; an index is at the back and is alphabetical.

catalog

A catalog is a separate list or book of items, often for sale; an index points to pages inside one work.

indicator

An indicator is a general sign of a situation, while an index is usually a measured number or an alphabetical list.

Word family

index noun

The base noun; its plural is "indexes" or, in technical writing, "indices".

index verb

To make an alphabetical list for a book, or to link a payment to rising prices.

indexing noun

The act or process of making an index, or of adjusting payments to an index.

Commonly confused: an index or appendix?

Practice

Make it your own

Write a sentence using “an index”, then check it and compare it with the examples above.

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