What is the plural form of 'index'?

The plural form 'indices' is derived from Latin, where the word 'index' originates. In academic and formal contexts, 'indices' is often preferred, especially in fields like mathematics, finance, and science, where precise terminology is essential. This form emphasizes the classical roots of the word and aligns with the way many Latin-derived nouns behave in terms of pluralization.

While 'indexes' is also acceptable and commonly used, particularly in general English usage, 'indices' is considered more sophisticated and is frequently used in scholarly writing. The other options provided, although they may sound plausible, are not recognized standard plural forms for 'index'. 'Indeces,' for example, is a misspelling and does not exist in the English language vocabulary. Therefore, 'indices' stands out as the correct and more formal pluralization of 'index.'