Here’s a test. What kind of music do you expect to see at a folk festival? Chances are you come up with images of Pete Seeger, Bob Dylan, and Peter, Paul and Mary.

Seems reasonable enough. Leftist leanings. Acoustic guitars. Poetic lyrics about idealism, politics and the people.

Don’t expect to see any of them at the National Folk Festival, however. The “folk” in this festival is less about the classic singer-songwriters who carry a torch for working-class life than it is about traditional music. And since we’re talking about polyglot America, the programming for the National can look like a virtual United Nations of performers.

Here’s a sampling from this year’s program: Maryland dieselbilly, Louisiana zydeco, Virginia bluegrass, hula dancing from Hawaii, Polish polka from Texas, blues and gospel from New York City, Gaelic music from Nova Scotia, opera from Tibet, salsa from Puerto Rico and jarocho music from Mexico.

That’s a long but instructive list when it comes to understanding the essence of an event promoters say could bring as many as 70,000 visitors to Bangor over a three-day period. Still, the term “folk music” can be as evasive as it is evocative. Typically, say former festival hosts, definitions can be prickly that first year, before anyone has attended the event.

“We struggled with the same thing,” said Judith Taran, communications director for the three years the festival was in East Lansing, Mich. “We said things like: It’s not Peter, Paul and Mary, or Arlo Guthrie. But you get into so many words for something that is so ephemeral. We never came up with any nifty definition.”

After the first year of the festival in East Lansing, however, the public came to understand that it was about traditional culture across the nation as well as within state lines.

“They saw for themselves that the festival was lively and fun, and fresh and modern and young – and that it also had old fiddlers,” said Taran. “That second year, people really got it and that’s when we saw our audience bump up in size.”

That’s what the Washington, D.C.-based producer has banked on since the first festival in 1934. The National Council for the Traditional Arts, which chooses the host locations and helps organize the event, relied on a local committee for recommendations about programming.

The festival’s deepest goal – in addition to presenting Maine material culture and world food – is to bring together the many musical sounds that have risen out of the confluence of cultures in North America.

“The music at the National Folk Festival is going to be music that comes from a community or a group of people that developed it on their own,” said Joe Wilson, executive director at NCTA and an award-winning leader, advocate and promoter of folk music internationally.

“Folk music is not just a style,” Wilson said. “It comes from a place, a family, an ethnic group. Folk is close to the bone. Much of what was called folk in the 1960s was the singer-songwriter style. You need that because a lot of the poets of our time are singer-songwriters. The music industry uses the label ‘folk’ for that singer-songwriter approach. And I love a good song but a singer-songwriter is not necessarily a folk singer by our definition.”

The definition, say some, is too narrow to represent the popular folk revivalist movement in this country.

“Folk is such a different term to different people,” said Linda Bolton, a music agent in New Mexico. “No one can seem to decide what folk is.”

Bolton faces this conundrum regularly with her clients, such as Dave Mallett, who plays acoustic guitar, sings about Maine life and has performed at many folk festivals throughout the country. She calls Mallett a “folk-singer-songwriter-poet” and adds that he “personifies rural life in Maine,” but worries that the organizers of the National won’t find musicians like him “traditional” enough to include on the program.

“For me, it means the freedom to work as a small-business man without trappings and an entourage,” said Mallett, adding yet another element. “I’ve always been my own boss and I’ve always been self-contained. I am a folk singer. I use the word to the fullest. I’ve never liked the word, but I am not afraid of it.”

Arnold Greenberg, whose now-defunct Left Bank Cafe in Blue Hill was once on the national folk circuit, gave an even simpler definition: “It’s just folks making music.”

John Bear Mitchell, a native studies teacher on Indian Island in Old Town and a Maine Indian who performs traditional and ceremonial music, said folk is “music that expresses the roots of a specific culture.”

And young Erica Brown, a Lewiston-based champion fiddle player who is both classically trained and has inherited her fiddling facility from a long line of French-Canadian musicians, says she is not certain what folk is. “I know it when I hear it,” says the 17-year old, who has a bluegrass band of her own.

Brown later said she had recently watched a videotape of her late grandfather, who played accordion and harmonica, performing a traditional tune called “Soldier’s Joy.” “That’s one of the tunes I play,” she said. “I hadn’t realized it was one that he played, too.” While she may be hesitant about defining folk, Brown has a true sense of having her art form passed on to her through the generations.

Clearly, the public and professional understandings of “folk music” are varied and complicated. The term itself, says Nick Spitzer, the folklorist host of National Public Radio’s music program “American Routes,” goes back to European Romanticism – “das volk” – for the peasantry who lived close to the land and were united by shared ancestry, religion and region. That, more than anything, is the template for the National.

“For this kind of folk festival,” added Spitzer, who is on the NCTA board of directors, “we find the artists who come out of a long historical basis in the region: Acadian fiddle music, Celtic music from Cape Breton, Native American music. It’s community-based cultural expression.”

That does not, however, indicate “folksiness,” as in primitive or unsophisticated.

“Sometimes things are called folk because they are not polished,” said Joe Wilson. “Of course, that’s an error because folk musicians are the most polished of all because their music comes from where it’s supposed to. All of us have heard that definition used for things that are awful and out of tune. But we have a hard set of rules at the National Folk Festival. If someone reaches for a note, they have to hit it. Our standards are very, very high.”

Bau Graves, co-director at the Center for Cultural Exchange in Portland, put it this way: “All this terminology tends to cause more confusion than shed light on the subject. Essentially, the folk in stores is by singer-songwriters. It’s not music made by the folk in a community. Probably few performers at the National Folk Festival would self-identify as folk. It’s a strange nomenclature. The kind of music that the festival brings in and that we validate in our programming here is an expression of some community and how it celebrates itself. It’s a collective creation. At the heart, it isn’t something you can stand up and say: ‘Picasso created this.’ There’s no one person who made jazz or old-time mountain music or Quebecois fiddle music. It’s really ethnic music.”

Spitzer, who lives in New Orleans and has family in Maine, added that one of the philosophical ambitions of the festival is to bring together traditional musicians from various regions – the Northeast, the South, the West and in between – to allow them a moment of cultural and aesthetic exchange.

“One of the festival’s secrets is that by being a movable feast, it tries to put together the artistic stories of parallel communities,” Spitzer said. “It opens up the senses. You’re saying to the Maine fiddler: ‘You’re something great, and by the way, here’s this blues guy from Chicago and he’s great, too.'”

Regardless of which definition you embrace – and even Wilson will tell you all of them are valid to some degree – the standard developed for the National has created one of the most respected and successful festivals in the country. Wilson grants that the name can be confusing, but he assures that the event focuses on a single mission: the preservation and proliferation of excellent music that comes from communities not only in America but in the Americas and beyond.