indices
C1-C2Formal, Academic, Technical
Definition
Meaning
The plural form of 'index', primarily meaning a system for measuring or indicating a level, or an alphabetical list.
Can also refer to the plural of 'index' in the anatomical sense (the finger) or in mathematics (a number expressing a property), though the latter often uses 'indexes'. Most commonly used for statistical or economic data series and database listings.
Linguistics
Semantic Notes
"Indices" is the traditionally Latinate plural, often preferred in scientific, economic, and technical contexts. "Indexes" is also a correct plural form and is more common in general computing contexts (e.g., database indexes) and in everyday usage.
Dialectal Variation
British vs American Usage
Differences
Both plurals are accepted in both varieties. However, "indices" has a stronger presence in UK English, particularly in academic and financial writing. US English shows a slightly higher tendency towards "indexes," especially outside of formal economics and mathematics.
Connotations
"Indices" connotes precision, formality, and technicality. It is the standard plural in fields like mathematics (indices of a formula), economics (stock market indices), and statistics (economic indices).
Frequency
In corpora, "indices" appears most frequently in financial, mathematical, and scientific texts. In general-purpose text, "indexes" may be more common.
Vocabulary
Collocations
Grammar
Valency Patterns
N + of + indices (e.g., a set of indices)V + indices (e.g., to track indices)Adj + indices (e.g., leading indices)Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “None directly; related to 'bellwether index' or 'leading index'.”
Usage
Context Usage
Business
Used frequently for market performance data, e.g., 'The FTSE and Dow Jones indices fell today.'
Academic
Common in mathematics (exponents), statistics, and economics for composite measurements.
Everyday
Rare; the simpler 'indexes' is preferred in non-specialist conversation.
Technical
Standard plural in optics (refractive indices), database theory (though 'indexes' competes), and finance.
Examples
By Part of Speech
verb
British English
- The database software indices the records automatically.
- They are currently indexing the archive.
American English
- The software indexes the files for faster search.
- We need to index the new data.
adverb
British English
- No standard adverbial form.
American English
- No standard adverbial form.
adjective
British English
- The indexical reference was unclear.
- He provided an index-linked pension.
American English
- The indexical reference was unclear.
- Her salary is index-linked.
Examples
By CEFR Level
- My textbook has two indexes.
- Look in the index to find the page.
- The library catalogues use different indexes.
- Check the index at the back of the manual.
- Economists monitor several key financial indices.
- The refractive indices of these materials are critical for the lens design.
- The model incorporates multiple volatility indices to assess risk.
- Comparing consumer price indices across nations reveals stark differences in inflation.
Learning
Memory Aids
Mnemonic
Think: 'Indices are for precise sciences' - both words end in '-ices'.
Conceptual Metaphor
A MAP or GAUGE (Indices guide us through complex data or measure abstract concepts).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with Russian "индекс" (index) which has the regular plural "индексы". The Latinate plural "indices" is analogous to Russian words like "индекс → индексы/инди́цесы" but the latter is very rare.
- Avoid overusing 'indices' where the simpler 'indexes' would be more natural in general contexts.
- Do not translate Russian "показатели" directly as 'indices' every time; sometimes 'indicators' or 'metrics' is better.
Common Mistakes
- Using 'indices' as a singular noun (incorrect: 'an indices shows...').
- Misspelling as 'indecies'.
- Using 'indices' for the plural of a book's index in a non-academic context, where 'indexes' is more idiomatic.
Practice
Quiz
In which context is the plural form 'indices' MOST traditionally preferred?
FAQ
Frequently Asked Questions
It is plural. The singular is 'index'.
Both are correct plurals of 'index'. 'Indices' is often used in technical, financial, and scientific contexts. 'Indexes' is more common in computing and general writing.
Yes, but 'indexes' is more typical and less likely to be marked as overly formal for that context.
It's pronounced IN-di-seez, with stress on the first syllable.