When Bob Pozen and I used “indexes” in the manuscript of our book, The Fund Industry: How Your Money is Managed — and our copy editor changed them all to “indices” — I ended up going back to “indexes,” partly because of personal preference, partly because I believed “indexes” is more common in our industry. But I wondered whether was an industry standard. . .
In favor of indices
Indices is the correct way to pluralize index in Latin, according to multiple sources on the Internet.
Grammarist says that indices is the most popular plural form of index outside North America. So, should North Americans go along? I agree with Grammarist: “…while it’s true that indices is the correct plural of index in Latin, index is an English word when English-speakers use it, so we can pluralize it in the manner of our own language.”
In favor of indexes
Reader comprehension is my number one priority. I think the average American will recognize indexes as the plural of index. I’m not so sure what they’ll make of indices.
Garner’s Modern American Usage says it’s pretentious to use indices. “For ordinary purpose, indexes is the preferable plural…,” says author Bryan Garner. However, he notes that indices is preferred by some writers in technical fields. If performance measurement is a technical field, then perhaps performance professionals can make a case for indices.
Indexes won in terms of number of appearances on Google. The term appears about 112 million times vs. about 88 million for indices.
Please answer the poll in the right-hand margin
What’s YOUR preference–indices or indexes? Please answer the poll in the right-hand margin of this blog. I will report on the results in my newsletter.