Klezmer may be one of the hottest thing in world music nowadays, but that’s definitely an odd contemporary phenomenon. Musicians who played klezmer music — klezmorim — have been on the lower rungs of the social ladder for some 600 years, according to Hankus Netsky, founder and director of the Klezmer Conservatory Band.

Proof: When the young Leonard Bernstein announced his intention of studying music, his father opposed it for fear that he would become a klezmer, said Netsky recently from his office at the prestigious New England Conservatory of Music in Boston, where he is a professor.

The great conductor Serge Koussevitsky actually paid his biographer not to mention that he came from a family of klezmorim. (The information leaked out anyway). And when Netsky himself began his band — which plays Sunday, Dec. 14 at Stanford’s Memorial Auditorium — it was one of just four in the entire country. Today there are hundreds.

So, what is klezmer? Actually it’s a construct, a little bit like zydeco, the 48-year-old musician explained. “It never really existed as a distinct style. It’s just a 20th-century way of talking about a kind of music.”

The word “klezmer” itself is a combination of two Hebrew words: klay (instrument) and zemer (music), literally meaning “instrument of song.” It referred to musicians — specifically wedding or court musicians — and can be found in the Bible. It carried an honorable connotation back in those days, deemed to be a gift from God. By the Middle Ages the words emerged in Yiddish, morphed into one, and referred to wedding and street musicians, mistrusted by the rabbis and less than respectable in the rest of society. Beginning in Germany and France, klezmer eventually spread to Eastern Europe and, in the 20th century, landed on these shores.

But there was little welcome. In 20th-century America, musicians, desperate to assimilate, did everything they could to get rid of the term, according to Netsky. It was first rehabilitated in Russia in the ’30s and, following the folk music revival in this country, was resurrected here in the ’70s.

“The American klezmer revival was very much a child of the folk revolution,” Netsky explained. “Jews who grew up hearing the funky roots music their parents were listening to finally looked around and said ‘Where’s ours?’

“And, ‘Fiddler on the Roof,’ with its romanticism of the shtetl, didn’t hurt. Then the third generation came along, looking for their grandparents’ music. Now it’s a phenomenon, but when I started in 1974, nobody wanted to talk about it. Now it’s accepted in academies. You can write your doctoral thesis on it.”

Paradoxically, klezmer may have its greatest contemporary popularity in Poland, a country with few Jews. Festivals, nightclubs, even weeklong klezmer performance camps have sprung up in the last decade.

“We were the first klezmer group to play in Poland in 1990,” Netsky said. “It was like this was their blues, their soul music. Jewish culture had been a kind of cornerstone of Polish culture and there was no Jewish culture anymore. They missed it. We got four and five encores and we never get four or five encores. Now there is a part of Krakow that’s like a klezmer theme park.”

Klezmer today can be just about anything, from the classical fusion style of the great clarinetist Giora Feidman to “Bei Mir Bist du Schon.” “There are all kinds,” Netsky continued: “downtown New York, traditional, jazzy … we’ve always been a repertory group with an eye on all of it.”

The Klezmer Conservatory Band even reaches into Greek folk melody and works with gospel choirs in its recordings, 10 to date, including the newly released “A Taste of Paradise.”

“The thing to understand is that it’s pretty wide open,” Netsky said. “The wedding musicians played whatever the people wanted to hear, including the popular music of the day. The thing that unites it is the style of interpretation. Whatever you’re playing, it comes out with a Jewish accent.

“It’s still a small thing, but it’s a miracle it exists at all. And it certainly has a place at the table in world music.”

The Klezmer Conservatory Band appears in concert 2:30 p.m. Sunday, Dec. 14, at Stanford University Memorial Auditorium, Serra Street across from Hoover Tower. Tickets are $30-$44; half-price for those 15 or under; discounts for students and groups. Information: (650) 725-2787 or http://livelyarts.stanford.edu.