Terrestrial radio: Don't touch that dial

Radio "shock jock" Howard Stern has found a higher calling. His paycheck, at least, will be higher. At the end of the year, he is moving to Sirius Satellite Radio, which will pay him half a billion bucks (yes, that's billion with a "b") over the next five years to do what his former corporate masters, Infinity Broadcasting, no longer seem enthusiastic about having him do over the public airwaves - especially not when they have to pay fines to the Federal Communications Commission.

A group of pundits were all cranked up about this on one of the Sunday morning talk shows last weekend.

Whether Howard Stern represents the cutting edge of public discourse in the United States, or a clear sign that the End of Civilization is near, I will leave to others for the moment. What particularly caught my ear was the phrase for the medium in which Mr. Stern has hitherto worked: "terrestrial radio." Maybe it was particularly striking because one expects the counterpart of "terrestrial" to be "celestial," as in "celestial navigation," for instance.

But Howard Stern - celestial? Nah.

"Terrestrial radio" is an example of a retronym - "a word or phrase created because an existing term that was once used alone needs to be distinguished from a term referring to a new development," as the American Heritage Dictionary of the English Language says. It's an awkward definition, but I can't easily do much better.

"Terrestrial radio": That's what your dad had, and probably your grandfather, too. It was a piece of furniture, and it sat in the parlor. Similarly, we have print newspapers, broadcast television, onshore oil rigs, and postal addresses (or snail-mail addresses, with their endearingly apt rhyme). We have analog watches, too. Actually "watch" has been through a couple of retronymic revolutions. In the beginning, a "watch" was a pocket watch. Then the wristwatch appeared on the scene, and the retronym "pocket watch" came into use. As wristwatches became the norm, they lost their modifier. Then the whole cycle started again with "digital watch."

Another kind of backward-looking language is "back-formation," which Merriam-Webster Online defines as "a word formed by subtraction of a real or supposed affix from an already existing longer word." Once again, the definition is easier to understand if you already know what the word means.

Here's an example: "to burgle." Although "burglar" sounds like one of the legions of "doer" words in English, meaning, we might suppose, "one who burgles," its "ar" ending should tip us off otherwise. "Burglar," literally one who breaks open a fortress, came first; it seems to be rooted etymologically in a sad metaphor of a household servant gone wrong. "Burglarize" is the more standard verb for what a burglar does; "burgle" is what the Etymological Dictionary Online calls "a hideous back-formation."

But hey, what's a growing language to do? We have new concepts and need new words for them, which we often adapt from words already in use. And that's how we end up with pairs like terrestrial and satellite radio.

And as for Howard Stern: Contrary to what some of the talking heads were saying over the weekend, he isn't really going "off the air." He's going "into space."

• This weekly column appears with links at http://weblogs.csmonitor.com/verbal_energy.