Rock ’n’ roll, at this point, is pretty much divorced from actual music.

Perhaps the funniest scene in the mostly mediocre “Walk Hard: The Dewey Cox Story” was the “birth of rock ’n’ roll” scene where Cox plays the most innocuous, Buddy Holly-style pop song at a high school talent show and incites a sexually charged riot. This smartly illustrates that what we once thought of as rock ’n’ roll doesn’t exactly fit the bill anymore.

Then again, rock ’n’ roll has never been pigeonholed into one particular era or moment in time, like, say disco or punk. Rock ’n’ roll isn’t necessarily more enduring; rather, I think it was never clearly defined in the first place. Imagine asking a friend what kind of music his band played and him responding, “Hey, man, we only play rock ’n’ roll.” It’s such a meaningless reply as to be this almost grandiose statement of purpose that’s just begging for a punch in the face.

Now rock ’n’ roll doesn’t even require an electric guitar. How many times have you heard that Barack Obama is a rock star? And every year on “American Idol” there is the designated rocker for both the men and the women contestants, and qualitatively, there’s very little difference between the rockers and the other contestants, except some weak attitude and dated sartorial decisions.

If you distill rock ’n’ roll, what you essentially have is attitude, sexuality and danger. Its bedrock was built on a few genuinely outsized personalities, and since then there’s been a lot of mimicry. It no longer matters if the personality or pose is genuine, which is not to say that it can’t be. But does anyone really care if Bowie’s Ziggy Stardust persona is sincere? It’s more a matter of how interesting the presentation.

Anyway, what made me think about this was catching the Kills live last week at a bar near my apartment. The two-piece band comprises Jamie “Hotel” Hince, a Brit, and Alison “VV” Mosshart, a Floridian. I saw the band live about six years ago before the two had even put out an album. They opened for another band and were so good that now I can’t even remember what band they opened for. I immediately bought their “Black Rooster EP.” Since then the Kills have put out three albums, with this year’s “Midnight Boom” being their latest and best.

Live, the Kills manipulate and have fun with an almost classical conception of rock ’n’ roll. Behind them on stage was grainy, black and white footage of, among other things, rock icons such as Patti Smith and Lou Reed playing live. The video projection was the sole frill. Otherwise there was just the two of them, VV and Hotel, kicking up a storm over an enormous, simple backbeat supplied by a drum machine. Hince piled licks upon licks until the lack of a back band didn’t matter and Mosshart vamped around the stage, occasionally donning a guitar.

The band’s reputation has been built on trashy, dirty rock ’n’ roll and fashion-victim images where both appear to be bored or pouty or bored and pouty. On stage, they definitely play up the implied sexuality of their music and boy-girl interplay with Hince putting his face right into Mosshart’s face while both are singing, their lips touching, but the intimacy could quickly become a violation of space as he appeared to, at times, almost be head-butting her as the song intensified. It was great, and, lordy lord, was it loud!

My girlfriend mentioned that Mosshart reminded her of a cheap Karen O of the Yeah Yeah Yeahs, but both toy with rock ’n’ roll conventions in different ways. Karen O inflates the rock star persona to its most glamorous, ridiculous extreme, while Mosshart plays it closer to the vest, a cross somewhere between P.J. Harvey, Patti Smith and Mick Jagger.

But both women are inventions, stage embodiments for their music, and proof that rock ’n’ roll in 2008 can still be entertaining.

Jeremiah Tucker writes for The Joplin (Mo.) Globe.