Indexes vs. indices

  • Indexes and indices are both accepted and widely used plurals of the noun index. Both appear throughout the English-speaking world, but indices prevails in varieties of English from outside North America, while indexes is more common in American and Canadian English. Meanwhile, indices is generally preferred in mathematical, financial, and technical contexts, while indexes is relatively common in general usage.


    Neither form is wrong. Both have been in English many centuries (and though indexes is now most common in American English, it predates the United States by centuries). It’s true that indices is the plural of index in Latin, but index is an English word when English speakers use it—and it is a longstanding one at that—so we can pluralize it according to the conventions of English.



    A quick tour around the world’s stock indexes will reveal the extent of Mr. Market’s New Year rethink. [Wall Street Journal]

    This year is looking tougher, though. Asian stock indexes are off to a rocky start with increasing concerns over rising inflation and other macroeconomic conditions. [New York Times]

    Indexes in idle mode: Stock rally fed by Europe deal slows [USA Today]



    Despite the fact we have major challenges of poverty, in all the indices of community engagement we are thriving. [Guardian]

    Of the 45 indices that make up the MSCI World Index, 36 recorded declines of more than 20 per cent. [Irish Times]

    For the average direct investor or trader, the market and the indices that represent it are almost completely irrelevant. [Sydney Morning Herald]

    Other resources

    “Indexes verses indices” at World Wide Words


    1. Thanks for the clarification!

    2. I arrived anticipating to read that “indexes” is wrong.
      Your explanation, “index is an English word when English-speakers use it”, is a good point.

    3. Nightshade says

      In Canada I have more often heard indices used – except in reference to stock markets (U.S. influence, I suppose).

    4. Demi Monde says

      Is it appendixes or appendices?

      • Articulation says

        Appendices, but it’s a bit different.

        For index to turn into indices it requires more of a transformation than appendix to appendices, where only the X is altered.

    5. David Achord says

      It’s only INDICES. Anyone that uses this purportedly acceptable term “indexes”, is a cretin.
      And not the good type of cretin, as referred to in the Ramones song, but the bad kind, . . . the kind you hate to go over to their house on holidays. And curse this author straight to hell for suggesting that Americans say “indexes” more than “indices”. That’s patently false.

      • Since we are using English, and not Latin, indexes is more logical.
        And to label someone a “bad type of cretin” and to wish eternal damnation on them (wishing them to go straight to hell), just because you don’t like a particular non-offensive word they use, shows how lacking in character you are.
        You need serious help.

    6. As a non native english speaker it was difficult to understand indices, that’s how I ended up here. I read it like “in dices” and couldn’t figure out what it meant. So my advice is to use indexes when targeting international readers.

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