During the global economic crisis of the last few years, previously esoteric financial jargon has worked its way into public discourse. One such term is quant, a shorthand term for "quantitative analyst." They're the subject of Scott Patterson's new book, The Quants: How a New Breed of Math Whizzes Conquered Wall Street and Nearly Destroyed It, and I take on the term in my latest On Language column in this Sunday's New York Times Magazine. It's a timely topic, given the mysterious 1,000-point dip in the Dow Jones index last week, variously blamed on quants and "fat fingers."

I first took a look at quant in a Word Routes column last November, "Going Quant, Going Rogue," where I mused on a piece in the Times that said that everyone is "going quant" in "the Age of Metrics." Quant as an abbreviation for "quantitative analysis" or "quantitative analyst" was new to me then, but since the publication of Patterson's book earlier this year, the term has received much more exposure. As Patterson tells it, the "quants" helped precipitate the financial meltdown when their model-driven strategies blew up in their faces and the exotic derivative investments they created went kaput.

Quants were back on the firing line last week, when the Dow Jones plunged nearly 1,000 points in a matter of minutes before recovering. The sources for this "flash crash" are still being investigated, but it seems to have originated in fears over the European debt crisis, exacerbated by "high-frequency" or "algorithmic" trading — a legacy of the quants — that now allows an enormous number of electronic trades to be transacted in the blink of an eye according to computer-driven methods.

As you also may have heard, there were rumors that the whole thing was set off by a so-called "fat-finger error" — a financial oopsy in which some unknown trader accidentally punched in "b" for "billion" instead of "m" for "million." (Or perhaps he held down the zero key a little too long?) The "fat-finger" theory was swiftly ridiculed (Jon Stewart predictably tore into it on "The Daily Show"), but it revealed yet another bit of surprising behind-the-scenes lingo to the public.

Fat-finger compound phrases, alluding to errors on a keyboard or keypad, go back at least twenty years. Such compounds can refer to intentionally mispunched keys, as in this line from a March 31, 1990 article in The Dallas Morning News: "Your college's phone bill has skyrocketed, because of student hackers using the 'fat-finger' method of pounding out a combination of phone codes to place unauthorized long-distance calls." And on his Wordspy website, Paul McFedries defines fat-finger dialing as "a telephone scam in which a company sets up a toll number that is one digit different than a popular number, so that the company earns money when customers accidentally mis-dial the legitimate number."

Previous market mishaps have been blamed on fat-finger errors, including a notorious trade on the Tokyo Stock Exchange in 2005. The incident brought to light so-called fat-finger syndrome, defined by The Guardian as "the occasional tendency of stressed traders working in fast-moving electronic financial markets to press the wrong button on their keyboard and, in the process, lose their employer a mint." Such are the new pitfalls in the era of the quants.

[Update: The "quants" column is now online here.]