Defining the perimeter of our parameters

I've put it off as long as I could, but I knew I finally had to confront the task: getting my head around parameter.

When I've run across the word, I've interpreted it as something akin to "aspect" or "dimension," and let it go. But I know that some experts sniff at those who use it loosely, without quite knowing its meaning. Hmm, let's not be one of those.

But I often have to confront as an editor words I can avoid as a writer. Parameter turned up in a book I was editing.

Parameter comes from Greek words meaning "beside" (as a paralegal, for instance, works beside a lawyer) and "measure." It was originally a term in geometry. Noah Webster defined it thus in 1828 – I'll quote, because I dare not paraphrase:

"1. The latus rectum of a parabola. It is a third proportional to the abscissa and any ordinate, so that the square of the ordinate is always equal to the rectangle under the parameter and abscissa; but in the ellipsis and hyperbola it has a different proportion.

"2. In conic sections, a third proportional to any diameter and its conjugate. In the parabola, a third proportional to any absciss and its ordinate."

Got that? I'm not sure I do, not even after studying the diagrams I found online. By the 1920s, though, parameter had come to refer to a "measurable factor" that helps define a "particular system."

And that's how my text was using it: "A parameter is one of the things we test for."

By the 1950s, what the Online Etymology Dictionary calls "the modern meaning" of boundary, limit, or characteristic factor had taken hold.

And this sense was influenced by another term with Greek roots, perimeter. "Peri" means "around." In the 1590s, a perimeter was a line around a figure or surface. By World War II, the word had a military sense: "boundary of a defended position."

It's when people use parameters to mean "limits" or "characteristics" that they get into trouble with the usage cops.

A usage note in the American Heritage Dictionary reads: "The term parameter, which originates in mathematics, has a number of specific meanings.... Perhaps because of its ring of technical authority, it has been used more generally in recent years to refer to any factor that determines a range of variations and especially to a factor that restricts what can result from a process or policy.... Some of these new uses have a clear connection to the technical senses of the word.... But other uses go one step further and treat parameter as a high-toned synonym for characteristic."

The development does not please the AHD's usage panel, 80 percent of whom rejected this example: "The Judeo-Christian ethic is one of the important parameters of Western culture."

Even curmudgeons have to accept that words evolve. But what to make of someone using a term of geometric art to say, "We work within the parameters of our budget," because he doesn't want to say, "We don't have enough money"?

It calls to mind the moment in Mark Twain's "The Prince and the Pauper," when the poor boy who has traded places with Prince Edward Tudor acknowledges using the Great Seal of England to crack nuts.

A commoner unschooled in matters of state didn't know how the seal was supposed to be used. But he saw how it could be used. And so it happens that a specialized term is grabbed and put to more mundane use.