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in·dex

(ĭndĕks′)

n. pl. in·dex·es or in·di·ces (-dĭ-sēz′)

1. Something that serves to guide, point out, or otherwise facilitate reference, especially:

a. An alphabetized list of names, places, and subjects treated in a printed work, giving the page or pages on which each item is mentioned.

b. A thumb index.

c. A table, file, or catalog.

d. Computers A list of keywords associated with a record or document, used especially as an aid in searching for information.

2. Something that reveals or indicates; a sign: "Her face ... was a fair index to her disposition" (Samuel Butler).

3. A character (☞) used in printing to call attention to a particular paragraph or section. Also called hand.

4. An indicator or pointer, as on a scientific instrument.

a. Mathematics A number or symbol, often written as a subscript or superscript to a mathematical expression, that indicates an operation to be performed, an ordering relation, or a use of the associated expression.

b. A number derived from a formula, used to characterize a set of data.

a. A statistical value that represents the price or value of an aggregate of goods, services, wages, or other measurable quantities in comparison with a reference number for a previous period of time.

b. A number that represents the change in price or value of stocks or other securities in a particular market, sector, or asset class.

c. The stocks or other securities represented by an index.

7. Index Roman Catholic Church A list formerly published by Church authority, restricting or forbidding the reading of certain books.

tr.v. in·dexed, in·dex·ing, in·dex·es

a. To furnish with an index: index a book.

b. To enter in an index.

2. To indicate or signal.

3. To adjust through indexation.

[Middle English, forefinger, from Latin; see deik- in the Appendix of Indo-European roots.]

index′er n.

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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Indo-European & Semitic Roots Appendices

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