Attempt to define “cabaret” and you’re asking for trouble. Happily, next week you’ll have a chance to see it firsthand when the Prince Music Theater joins forces with New York’s Mabel Mercer Foundation to present four nights of this elegant -- and endangered -- art form. Dozens of performers, including major stars like Christine Andreas, Andrea Marcovicci and Wesla Whitfield, will prove that Life is indeed A Cabaret.

Until then, let's start with Donald Smith's appealingly simple explanation: "It's performances of the great American songbook." (Smith is executive director of the Mabel Mercer Foundation, and cabaret's guardian angel.)

Certainly, every cabaret singer is judged on both performance and repertoire. How many songs does she know? Does each concert set have just the right balance of familiar favorites and little-known gems? If you're planning a career in cabaret, you'd better know dozens -- no, hundreds -- of them. (Start with Rodgers and Hart, Alec Wilder and of course, Cole Porter and Stephen Sondheim.)

But isn't cabaret also about the style of the performance? The intimacy of the venue? Well... yes and no.

Great cabaret singers sometimes have great voices (Andreas does -- so does Barbara Cook, one of her idols), but not always. The late Mabel Mercer, cabaret's acknowledged goddess, once had a great voice -- but some of her most memorable performances were given when that voice was a shadow of itself.

What Mercer had -- and all great cabaret performers strive for -- is the gift to connect in an almost mystical way to a great lyric, and to present each song as a miniature piece of theater. Sounds easy, but trust me, it's not.

"It takes thinking!," says Whitfield, about how she approaches a song. "I always start with the lyrics. It helps to have a good tune, but it's got to be in the words." Do you ever avoid a song with a great melody because you don't love the lyrics, I ask? "Sure," she says, dryly adding, "It has created some heated discussions at home." (Whitfield's husband is her music director, Mike Greensill, an outstanding jazz pianist in his own right.)

For Andreas, well known as an actress and musical theater performer, cabaret offers a different challenge. "You're on stage alone for 75 minutes. Where you are with yourself is completely obvious. My job is to get out of my own way, to be totally present. If I can do that, I know I'm really singing."

Whitfield and Andreas are smart, articulate and passionate. No surprise -- it takes brains to be a cabaret singer. It also takes scholarship, and both performers regularly refer to the history and tradition of their art. Andreas mentions with awe not only Barbara Cook, but also Rosemary Clooney and Julie Andrews. When I ask Whitfield about a particular song, she tells me firmly that she won't touch it -- "that's really a Mabel Mercer piece."

Mercer again. She famously performed while seated, creating the illusion that she confided in the listener: Every word seemed precious and overheard. She held court in tiny rooms, which comes back to the question of intimacy. Some people think that cabaret can only work in a nightclub.

Yet Smith and the Foundation have had great success in bringing cabaret to larger venues and bigger audiences. This year will see the 13th annual cabaret convention in New York, and it's nearly certain that every show will sell out months in advance. More recently, Smith has expanded his horizons, bringing cabaret conventions to San Francisco, Chicago and now Philadelphia. Attendance is terrific, audience reaction even better. (Smith also points out that Mercer had some of her greatest success in concert at New York's Town Hall, now the home of the convention. "The great artists make any venue feel like a supper club," he says.)

It's a necessity, Smith explains. "Years ago, there were great rooms in all the major cities on the East Coast. A singer could get engagements along the circuit and earn a living." But many of those clubs are gone now, and making a living -- even for some of the most prominent cabaret artists -- isn't a sure thing.

So the cabaret conventions were born. Smith started it as a labor of love and to honor Mercer, whom he cared for during the last 20 years of her life. "She was my family, and I was hers," is how he puts it.

Each evening, a group of perhaps 10 performers will do several songs each. Some programs have themes ("Cabaret at the Movies," a tribute to Cole Porter), while others are more open-ended. Each one brings together established artists and a few newcomers (including some local talent).

Cabaret's back in Philly. Let's hope it's the beginning of a long and happy association.

Philadelphia Cabaret Convention, Thu., June 6 through Sun., June 9, $45 for each show, Prince Music Theater, 1412 Chestnut St. For full schedule see www.prince music theater.org or call 215-569-9700.