Unless you've been living in a spider hole, it will neither shock nor awe you to learn that military slang has become increasingly, uh, embedded in American popular culture.

Although hardly a new phenomenon--the military has been a source of American slang since the Revolutionary War--it does seem to be having a growth spurt. Ever since the World Trade Center was designated "ground zero," it has been (damn the torpedoes) full speed ahead for military jargon.

Not all of it reaches catch-phrase status. Some phrases, like old soldiers, simply fade away. Such, thankfully, was the case with Secretary of Defense Donald Rumsfeld's "known unknowns." Others hang on to become part of our everyday vernacular.

Time will tell which will be the case for the latest military metaphor to hit the airwaves--one that has been bandied about by no fewer than four of the participants in the recent 9/11 hearings:

"Hair on fire."

A sense of urgency

That odd phrase, believed to have originated among Navy aviators intending to convey a sense of hair-raising urgency, quickly became the phrase of the day as hearings began before the commission investigating events that led to 9/11.

First it came from Richard Ben-Veniste, a commission member recounting allegations that President Bush ignored Al Qaeda before the attacks, despite warnings from alarmed officials.

Then Rumsfeld used it, saying such alarm wasn't uncommon. Clarke, the Bush critic who appeared before the commission, uses the phrase at least twice in his new book, "Against All Enemies," Chapter 3 of which begins: "Charlie Allen had his hair on fire."

The repeated allusions to burning coifs were enough to make one wonder, amid the far more important questions the hearings are raising, just where that phrase came from.

Capt. Earle Rogers, a retired Navy flier who is vice president for communications at the Naval Air Museum Foundation in Pensacola, Fla., said the phrase goes back at least 25 years.

"I think the term is probably specific to naval aviation," he said. "It's one we all understand."

But what does it mean?

"Just what it sounds like," Rogers said. "You use it to describe one of those days that are just so frustrating, where you have so many balls up in the air, and you're trying to juggle so many things."

Frantic?

Like, that, but more under control. "It's like when you're going around in tight, tight circles ... trying to keep out of the way of enemy fire. Your hair can be on fire, but you still land the plane safely."

As with most slang, its precise origin is difficult to pinpoint, and interpretations of it vary. Some use it to describe chaos, some use it to describe alarm, some use it to describe the edgy thrill of being a fighter pilot.

"This is the problem with slang," said John Reilly, an historian at the Naval Historical Foundation in Washington. "It's casual, it's informal. It's not like a memo goes out: From chief of naval operations to all hands, henceforth this will be called `hair on fire.'

"There are all kinds of words and phrases that have naval origins, or are related to the military, or weaponry--`half-cocked,' `lock, stock and barrel.' In the Civil War, if you'd been in combat, you'd `seen the elephant,"' he said.

Ancient Buddhists

Although Navy aviators may have brought the phrase into more common use, references to "hair on fire" can be found much earlier--from the teachings of ancient Buddhists to the 1939 James Joyce novel "Finnegan's Wake."

Joyce was clearly--to borrow some more aviator jargon--pushing the envelope when he wrote: "The Flash that Flies from Vuggy's Eyes has Set Me Hair On Fire, His is the House that Malt Made, Divine Views from Back to the Front, Abe to Sare Stood Icyk."

Ancient Buddhist wisdom--a little easier to grasp than Joyce, or, for that matter, Rumsfeld--holds that a person should seek enlightenment in the same way a person whose "hair is on fire" would seek water, meaning with the utmost urgency.

It was in 1986, though, that "hair on fire" got its biggest boost--being used in a line from that year's top-grossing movie, "Top Gun."

"You're not going to be happy unless you're going Mach 2 with your hair on fire," Kelly McGillis (instructor Charlotte Blackwood) says to Tom Cruise (Lt. Pete "Maverick" Mitchell).

Nowadays, you can find the phrase being used for everything from describing the play of athletes to a Web site that promises "hair-on-fire marketing programs."

How such oddball phrases become universal is mostly a matter of simple repetition. Bureaucrats repeat each other. Journalists--embedded and unembedded--repeat bureaucrats, then repeat each other, then start being repeated by bureaucrats, who are repeated by still more journalists and, eventually, the general public.

Look, for instance, at what happened with "ground zero."

No one knows who first used it to describe the site of the 9/11 attack, but the term--originally used by weapons testers in 1946 to define the point directly beneath a nuclear detonation--quickly became universally accepted as synonymous with the rubble that remained of the World Trade Center.

Then there was "shock and awe," the Bush administration's name for its strategy to invade Iraq. First it was used in the media. Then it was overused, appearing everywhere from the food pages to the sports pages and becoming an instant cliche in the process.

After that came "spider holes."

From Vietnam to Iraq

When Saddam Hussein was found hiding in a hole in the earth, an Army official described it as "a spider hole," a term used by the Army during the Vietnam era.

The holes, in which Viet Cong hid inside clay pots to ambush American troops, were so named because, if the pots broke, the guerrillas were subject to bites by poisonous spiders.

The term appeared in news accounts about Hussein's arrest, then took on a life of its own, being used--in the media as well as everyday conversation--to describe anyone who was out of touch or keeping a low profile.

"Something can become a cliche almost immediately now," said Robert J. Thompson, a professor of popular culture at Syracuse University. "Look what happened with `wardrobe malfunction.'

"Within 24 hours it was in use around the country and the world. But becoming a cliche and staying a cliche are two different things. Sometimes, the ones that have incredible bursts, that erupt almost spontaneously, don't make it to the end of the year."