In January, KLD Indexes entered into a strategic partnership with FTSE Group, a London-based firm that "calculates over 120,000 indices covering more than 77 countries and all major asset classes."

You see our problem. Trans-Atlantic business partners can turn dollars into pounds, exchange labor for labour, and enjoy both kinds of football – but what is the plural of index? Tom Kuh, Managing Director of KLD Indexes, put the question to some of us at KLD world headquarters in Boston. On one side: FTSE. On the other: my New York Times style guide, which says simply: "indexes (not indices)."

We split pretty evenly. Hoping for a tiebreaker, I searched Barbara Wallraff's "Word Court" at The Atlantic. I didn't find an answer, but she does offer some salient wisdom from the late John Updike:

"Facts are generally overesteemed. For most practical purposes, a thing is what men think it is. When they judged the earth flat, it was flat. As long as men thought slavery tolerable, tolerable it was. We live down here among shadows, shadows among shadows."

For those who think there's only one right answer to the question, "Which word?" note that MS Word doesn't think John Updike should write "overesteemed."

And for those who deny that such questions should lead to a good-natured discussion, Mr. Updike again:

"We take our bearings, daily, from others. To be sane is, to a great extent, to be sociable."

Indexes or indices? Feel free to cast your vote, sociably, in the comments.