Groovy. Ouch. Awesome. So 1980s. Phat. Who you trying to fool, fly boy? The approbations of popular culture have a limited half-life, and the wrong word can mark you as a fossil of some blessedly forgotten decade.

But there is one word in the English language that has defied the rise and fall of fashion. Cool endures.

Part of my job involves attending numerous conferences on ministry. Incidentally, I've started to classify these events by dress code and the amount of hair gel used by the men in attendance. Khakis and sweaters and the natural look? Must be a megachurch training event. Brilliantly polished leather shoes and close shaves? T. D. Jakes is sure to be on the roster.

Anyway, at a recent distressed-jeans, multiple-piercings forum, I'm talking with a 25-year-old pastor who appears to drive up the average hairstyling bill in the room by several dollars. "Yeah," he says, "we're starting a church for cool people."

Cool people?

"Yeah, you know, people like us." (He doesn't mean himself and me; he means himself and his friends—all of whom do indeed exude a level of coolness that I could only dream about.) I fleetingly envision spot checks at the door—Old Navy allowed only on probation, white sneakers politely referred to the contemporary service down the street—but decide that coolness is probably self-enforcing.

Later in the weekend, after one of my presentations, he admiringly says—I swear this is an accurate quote—"You know, dude, you may not have cool hair, but you have some serious clue." (What a relief—the cool kids like me!)

Now, I promise that 15 years from now, my interlocutor will neither sport his current hairstyle nor use the phrase "serious clue" with a straight face.

But I'll bet that he—and I—will still say "cool." ...