Indices vs Indexes: What's the Difference

The terms “indices” and “indexes” are often used interchangeably, but there is a subtle difference between them. The choice between these two words depends on the context in which they are used and the preferred style of the writer or publication.

In general, “indices” is the preferred plural form of “index” in many academic and technical fields, such as mathematics, economics, and statistics. For example, a mathematician might refer to the “indices” of a matrix, while an economist might discuss the “indices” of economic activity.

On the other hand, “indexes” is often used as the plural form of “index” in more general or informal writing, such as in journalism or everyday conversation. For instance, a journalist might write about the “indexes” of a book, while a casual conversation might involve discussing the “indexes” of a website.

It’s worth noting that both “indices” and “indexes” are acceptable plural forms of “index,” and the difference between them is largely a matter of style and convention. However, in certain fields or publications, one form may be preferred over the other.

To illustrate the difference, consider the following examples:

• In a mathematical context, a writer might use “indices” to refer to the plural form of “index”: “The indices of the matrix are used to calculate the determinant.”
• In a more general context, a writer might use “indexes” to refer to the plural form of “index”: “The book includes several indexes to help readers find specific topics.”

Ultimately, the choice between “indices” and “indexes” depends on the writer’s personal preference, the style guide being followed, and the context in which the word is being used.

Historical Evolution of “Indices” and “Indexes”

The words “indices” and “indexes” have a long history, and their meanings have evolved over time. The word “index” comes from the Latin “indicem,” meaning “a pointer” or “a sign.” In the 16th century, the word “index” was used to refer to a pointer or a sign that indicated something, such as a finger pointing to a specific location.

Over time, the word “index” took on additional meanings, including a list of words or phrases with their corresponding page numbers, as well as a statistical measure of a particular economy or market. As the word “index” became more widely used, the need for a plural form arose, and both “indices” and “indexes” emerged as acceptable options.

Technical Breakdown: When to Use “Indices” vs “Indexes”

In general, “indices” is the preferred plural form of “index” in technical or academic contexts, while “indexes” is more commonly used in general or informal writing. Here are some guidelines on when to use each word:

• Use “indices” in:
  • Mathematical or statistical contexts, such as referring to the indices of a matrix or the indices of economic activity.
  • Academic or technical writing, such as in economics, finance, or computer science.
• Use “indexes” in:
  • General or informal writing, such as in journalism or everyday conversation.
  • Non-technical contexts, such as referring to the indexes of a book or the indexes of a website.

Expert Insight

According to linguist and language expert, John McWhorter, the choice between “indices” and “indexes” is largely a matter of style and convention. In his book, “Words on the Move,” McWhorter notes that both words have been used as plural forms of “index” for centuries, and that the difference between them is largely a matter of personal preference.

Decision Framework

To decide which word to use, consider the following factors:

• Context: Are you writing in a technical or academic context, or a more general or informal one?
• Style: Are you following a specific style guide, such as the AP Stylebook or the Chicago Manual of Style?
• Personal preference: Do you have a personal preference for one word over the other?

By considering these factors, you can make an informed decision about whether to use “indices” or “indexes” in your writing.

FAQ Section

In conclusion, the choice between “indices” and “indexes” depends on the context, style, and personal preference. By understanding the historical evolution of these words, their technical breakdown, and the expert insights on their usage, writers can make informed decisions about which word to use in their writing.