Indexes vs Indices: Difference and Comparison

In English, there are words that have more than one variant and it’s sometimes difficult to choose between these words. For example, some people are often confused about whether to use indexes or indices (indexes vs indices).

Well, indexes and indices are plural forms of the term “index”. However, the term “indexes” is often used in general context, whereas “indices” is the preferred term used in mathematical and financial contexts.

The term “indexes” is commonly used in American English, while “indices” is a preferred term used in British English.

In this article, we have defined both terms and highlighted the difference between indexes and indices.

Indexes

The English dictionary defines the term “index” as an alphabetical listing of items and their location. For example, the index of a book lists words or expressions and the pages of the book in which they are to be found.

Hence, indexes are commonly found in contexts like reference works and databases. The term “index” is often commonly used as a benchmark to assess the performance of a portfolio or an investment.

An index can be comprised of bonds, commodities, stocks or other assets. An index is often calculated as a weighted average of the prices or values of the components- Indexes are important in the financial industry, and commonly used as a reliable tool to monitor the performance of a sector or market.

Additionally, indexes can be used as a basis to create investment products like exchange-traded funds (ETFs) or mutual funds.

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Indices

The word “indices” is also a plural of the term index. Both indexes and indices have the same meaning, only that the former is a preferred term in American English, while the latter is often used in British English.

Unlike indexes, the term indices is not commonly used in the financial industry. While indexes are a preferred term used in the financial industry, indices are commonly used in other fields like mathematics, science, or linguistics.

Indices are often used in mathematics to denote the power to which a variable or number is raised- i.e. the expression 3^4, the number 3 is the base and 4 is the index. This means that 3 is multiplied by itself four times.

Indices are also used in science mainly to denote a particular property or characteristic of a substance or a specific system. For example, in optics, the refractive index is the measure of the bending of a ray of light when passing through from one medium into another.

In linguistics, indices are often used to describe a pronoun that typically refers to a certain referent in a discourse- for example, in this sentence “Rodney said he would stay behind” “he” is an index that refers to Rodney in the sentence.

Indexes vs Indices: Key Difference between Indexes and Indices

Indexes and indices are plural forms of the term “index”- the Index is the alphabetical listing of items and their location. For example, the index of a book lists words or expressions and the pages of the book in which they are to be found.

Hence, indexes are commonly found in contexts like reference works and databases.

Generally, plurals of nouns take different rules and only some nouns need an –s or –es at the end of the word. The plural of other nouns needs a change in spelling. However, some nouns such as “index” follow both rules.

Indexes are the preferred and general term mostly found in contexts such as book listings, databases, or reference works. In contrast, indices are generally used in mathematical, linguistics, or scientific contexts.

Indices is the preferred term when talking about stock market measurements or mathematical sequences. Although indexes and indices are generally preferred in different contexts, both terms are grammatically correct and their usage sometimes overlaps.

Both terms indexes and indices are the plural forms of the term “index”. They are plural forms of the word “index”, but the contexts in which both terms are generally used differ.

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Indexes vs Indices: When to Use Indexes and Indices

When is it appropriate to use indexes?

Both terms indexes and indices are the plural forms of the word “index”. The main difference between indexes and indices is that the former is the Anglicization of indices.

It’s appropriate to use the term “indexes” in your writing as a non-technical plural form. However, some books that offer insight into formal writing settings prefer to use “indexes”.

Experts in linguistics agree that is appropriate to use “indexes” when you are referring to bibliographies, citation listings, and other written files.

Also, it’s more appropriate to use indexes over indices, especially if you are following the AP style guide.

When to Use Indices

The term “indices” is commonly used in British English over indexes.

Indices is said to be the irregular plural form of the term “index”. Technical contexts often prefer the term “indices” over “indexes”.

Indexes are preferable for popular writing, while the technical use of indices is more suitable in statistical contexts.

Indexes vs Indices: How to Use Indexes and Indices in Sentences

Let’s look at a few examples with the term “indexes”.

The stock market indexes are generally used to measure the performance of the overall market.
The institution’s library has a large index of books on different topics.
Jane used the index at the back of the book to find the pages she was looking for.
The index finger is the second digit of the hand and it’s typically one of the most often-used digits.
The news reported that the stock market index reached an all-time high in the last few days.
Sometimes the index of a book is overlooked, but it’s a reliable tool for finding information in no time.
The corporation’s financial index showed an increase in profits.
According to meteorologists, the weather index predicts a high probability of rain in the coming days.

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Using the term “Indices” in a Sentence

The indices on the map help the explorers navigate through the jungle.
The corporation tracks a variety of indices in order to monitor market trends.
According to experts, the economic indices suggest that the country is on the verge of a recession.
Medical experts suggest that the disease can be diagnosed through blood indices.
The indices of the stock market indicate a significant decline in the technology sector.

Indexes vs Indices: Comparison Chart

	Indexes	Indices
Etymology	Latin origin	Latin origin often associated with specific fields
General usage	Commonly used in general context	Preferred in mathematics, linguistics or science.
Mainly used in	American English	British English
Example usage	Book indexes, database indexes and reference work indexes	Stick market indices, mathematical indices
American English	More universally accepted in modern contexts	Used in specific disciplines
Grammatical correctness	Indexes and indices are correct plural forms of the term “index”	Indexes and indices are correct plural forms of the term “index”

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Indexes and Indices: Using Indexes and Indices Interchangeably

A common mistake most people make is to use indexes and indices interchangeably.

The term “index” is an alphabetical listing of items and their location. For example, the index of a book lists words or expressions and the pages of the book in which they are to be found.

Hence, indexes are commonly found in contexts like reference works and databases.

The term “index” is often commonly used as a benchmark to assess the performance of a portfolio or an investment.

In contrast, indices are commonly used in other fields like mathematics, science, or linguistics. Indices are used to represent a specific set of data or a range of values.

Conclusion

Indexes and indices are plural forms of the term “index”. However, the term “indexes” is often used in general context, whereas “indices” is the preferred term used in mathematical and financial contexts.

Indices is the preferred term when talking about stock market measurements or mathematical sequences.

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References

Writingexplianed: Indexes or Indices – What’s the Difference?
Grammarist: Indexes or Indices – The Plural Debate