It’s a funny thing, what’s happened to the word “musical.” Like “novel,” this simple adjective has grown into a giant noun encompassing an entire art form. But even as the term has inflated, the form itself seems to have shrunk. Even after Rent, even after “Glee,” the American musical has a particular vocal and compositional sound, and we all know it when we hear it.

For all their pleasures, and for all the crowds musicals continue to pack in, stage music itself has become a niche genre, and apart from a devoted cadre of show fans, it’s not what most of us choose to listen to on our iPods, on our Pandora stations, in concert halls or on our party playlists. Indeed, though it’s got the word “music” inside it, the varieties of music typically excluded by that innocent little word, “musical,” could fill several lifetimes of listening—and for many audiences stubbornly immune to the charms of musical theatre, they do.

Arguably, there’s new blood pumping into the form via so-called “jukebox” shows, which range from bio-concerts (Fela!, Million Dollar Quartet) to broadly narrativized samplers (Movin’ Out, Rock of Ages, Mamma Mia!); or via theatricalized concept albums, like Green Day’s American Idiot or Matthew Sweet’s Girlfriend (both originally mounted at Berkeley Repertory Theatre before moving on, to Broadway and to Actors Theatre of Louisville, respectively). That pop stars like Elton John and U2 have conquered Broadway may be most notable in how exceptional their cases are. And the fact that not-so-huge stars like Duncan Sheik (Spring Awakening), Lin-Manuel Miranda (In the Heights) and Tom Kitt (Next to Normal) have pressed pop sounds into fresh storytelling service is certainly some cause for hope.

But perhaps the most heartening and transformative trend in American musicals—and we might as well reclaim the word, all the better to broaden its purview—is a swelling wave of hybrid shows created, and often performed, by indie bands and singer/songwriters. Some begin as staged concept albums (the Lisps’ Futurity, Walter Sickert & the Army of Broken Toys’ 28 Seeds, Black Francis and the Catastrophic Theatre’s Bluefinger). Some begin as devised-theatre pieces in which live music is as integral as the script (PigPen’s The Old Man and the Old Moon, Young Jean Lee’s We’re Gonna Die). Some begin as quasi-cabarets built around performers with stories to tell and/or roles to play (Stew and Heidi Rodewald’s Passing Strange, Ethan Lipton’s No Place to Go, and the granny of them all, Hedwig and the Angry Inch). Some even begin as essentially traditional musicals, but with the clear stamp, and often the actual presence, of their composer/performers (Glen Hansard and Markéta Irglová’s Once, Dave Malloy’s Natasha, Pierre & The Great Comet of 1812, Groovelily’s Sleeping Beauty Wakes).

None are Broadway-tooled properties by brand-name stars, though some (Once, Passing Strange) do end up on the Main Stem. And while most are mere flickers on the radar of the nation’s resident theatres and play-development houses, that is rapidly changing. In a trend analogous to the way “devised” ensemble work is increasingly welcomed by institutional theatres (see “Group Think,” March ’13), bands and actor/musicians are teaming with directors, playwrights and dramaturgs as full partners on new stage pieces, not simply rolling their gear through the stage door just before tech rehearsals to play through scores fully notated by a single composer.

It was César Alvarez, the lanky, curl-topped frontman for the folk-rock band the Lisps, who floated an analogy between novels and musicals in a recent interview. Since he and his band wrote Futurity, a concept album about the Civil War–era inventor of a steam-powered artificial intelligence, which was staged last year at Cambridge, Mass.’s American Repertory Theater and at Minneapolis’s Walker Arts Center (and will hit New York in 2014–15, with Soho Rep co-producing), they’ve been bitten by the theatre bug. They recently scored and appeared in the Foundry Theatre’s Off-Off Broadway revival of Brecht’s The Good Person of Szechwan, and they’re developing a show with Soho Rep artistic director Sarah Benson at Berkeley Rep’s Ground Floor. And while the Lisps still tour and record, Alvarez now thinks of himself, at least in part, as a theatre artist.

“Musical theatre has become a genre, but it’s actually not a genre!” exclaimed Alvarez, climbing on what is clearly a favorite hobbyhorse. “You hear from musicians all the time, ‘Oh, I hate musicals,’ which is like saying, ‘Oh, I hate novels.’ It would be as if somebody invented the novel, and then for hundreds of years, the only kind that became popularized was the mystery novel.” He feels that the American musical has been similarly constrained, sonically and aesthetically: “The classic musicals, they’re classics—but they don’t encompass the entire spectrum of what musical theatre can be. That’s why I say musical theatre has been genre-fied in a way that is a complete disservice to the form. It’s basically music, dialogue and narrative on a stage, telling a story. That’s it! It doesn’t say how to sing or what kind of music.”

In the case of Futurity, what began as a staged concert at New York’s Zipper Factory blossomed into a play-with-a-band, with Alvarez and singer Sammy Tunis taking lead roles and drummer Eric Farber sitting at the helm of a contraption he constructed called the Steam Brain—which Alvarez described as a “handmade percussion machine which is a musical instrument, a storytelling device and an interactive set-piece.” The style of the score, true to the Lisps’ artisanal indie-rock sound, encompasses twangy folk, old-timey Americana and pristine chamber pop. And the style of the piece, even as it’s added a script, by Alvarez and playwright Molly Rice, is still centered around the Lisps’ presence.

The challenge, as director Benson put it, was “trying to figure out how to keep it being a show where the band was telling the story, and yet blow it out into a musical. When I was stuck, I would just think, ‘What would the Lisps do?’ Casting solutions, design solutions—all came out of that musical language.”

A musical lexicon is certainly what Stew and Heidi Rodewald developed in the band the Negro Problem, but it wasn’t until Bill Bragin, the former director of the Public Theater’s in-house nightclub, Joe’s Pub, recognized the theatricality of the duo’s wry, tuneful songs and Stew’s crackling stage patter, that they “stumbled into a whole other career,” as Stew recently put it. The resulting show, Passing Strange, moved through Sundance Institute Theatre Lab, Berkeley Rep and the Public before landing on Broadway, where it didn’t run long but spawned an HBO movie and garnered a Tony for Stew’s book. Now Stew and Rodewald are in the midst of three new musical theatre projects: The Total Bent, a show for the Public in which they don’t appear; a commission from the Oregon Shakespeare Festival for an autobiographical show called Family Album (in which they may appear); and one for Washington, D.C.’s Studio Theatre.

Meanwhile, at Joe’s Pub, in the wake of Passing Strange, Bragin’s successor, Shanta Thake, has helmed an NEA-backed commissioning project called New York Voices, which brings together musicians with directors and playwrights and puts the Public’s dramaturgical resources at their disposal. Funded work has included Lipton’s No Place to Go, as well as shows by such artists as Lady Rizo, Toshi Reagon, Angelique Kidjo and Abigail Washburn. With all of them, Thake said recently, the point is not to create a one-size-fits-all template but to be sure that “what makes the performers amazing is at the center of the show.”

Indeed, retaining the aesthetic imprint of the writer/performers is the key distinguishing feature of this hybrid form. That’s not because having the artists perform what they’ve written is a huge marquee draw, since most of them are not widely known; it has more to do with the immediacy and integrity, and the fresh, unstudied theatrical energy that a seasoned band can bring to the stage.

“I think all music performers are actors,” declared Stew, as ever a voluble, Falstaffian figure. “Every guy in a band who knows that 500 people are watching him is not going to stand exactly like that when he’s at home. But the beauty of musicians as actors is that they’re really smart actors—they’re smart enough to know that the game is really making it look like it’s natural.”

Alvarez, for one, sees a historical analogy.

“It’s really amazing to hear Frank Sinatra do a Cole Porter song, but it’s also just as amazing to hear the Beatles play the Beatles,” he said. “That was the big revolution that happened in pop music, and I honestly think there’s a thing happening in musical theatre, which is that it’s incredible to watch the people who made the thing do the thing. And that’s what you get when you see a band perform a musical.”

There’s also a literal immediacy to the band model. The folk/pop trio Groovelily was formed in 1994 when Brendan Milburn, a student in New York University’s musical theatre program, found himself “cowed and freaked out about how long it took, from putting pen to paper, how much money and how many people, to get a musical up.” Then he met the electric violinist Valerie Vigoda and marvelled that “she would write a song that day and play it that night at Sidewalk Café. With a band, you can get from writing to performing very quickly.”

Indeed, Groovelily, which includes drummer Gene Lewin, completed their first show—the alternative-holiday piece Striking 12—in the van on the way to the first rehearsal at Philadelphia’s Prince Music Theater in 2002. But while Groovelily’s members are still central to their shows’ creation and initial performances (including the autobiographical Wheelhouse at Palo Alto, Calif.’s TheatreWorks, and the new La Jolla Playhouse/TheatreWorks commission Ernest Shackleton Loves Me), they know that to build a career in the theatre is to create license-able properties, as surely as building a career in music means (or used to mean) creating a catalogue of published songs and recordings.

“If you write a show so only you can perform it, you’re really limiting the future of that show,” said Milburn. “From pretty early on, our literary agent was pushing us to take Striking 12 and turn it into something else. Not every high school has a singing electric violinist.”

Among Groovelily’s New York berths has been the new-work incubator Ars Nova, a club/theatre space that has nurtured its share of performer-created musicals, from the pirate/puppet romp Jollyship the Whiz Bang to Malloy’s Natasha, Pierre & The Great Comet of 1812. Ars Nova’s artistic director, Jason Eagan, acknowledges the appeal of creator-performed shows but believes that works of substance can survive recasting.

“In writing Natasha, Dave put himself in the middle of it,” conceded Eagan of Malloy’s pulsing, through-sung adaptation of a section of Tolstoy’s War and Peace, in which the composer conducts an ensemble of actor/musicians and performs the pivotal narrator/actor role of Pierre. The show, which Malloy said he wrote in a mere 18 months or so (immediacy!), ran last fall at Ars Nova and will reopen Off-Broadway on May 1. “And yes, there’s something about seeing Dave at the center of the piece that is very cool and exciting. We’ll be able to say, ‘We saw Dave himself do it’; I can imagine if we saw Sondheim do Merrily We Roll Along, that would be pretty exciting, too. But as with Hedwig, the role he’s written for himself feels very three-dimensional—it’s something that an actor could take on.”

Going the other direction, from theatre to music, is form-breaking playwright Young Jean Lee, who wrote and performed her odd, endearing indie-rock cabaret We’re Gonna Die with a band for a full run at Joe’s Pub in 2011, and is now touring it internationally. Though in her rendering, the show—in which she ostensibly treats her childhood, her parents, dating and death—had an intimate, disarmingly personal feeling, she said she wrote it “so that it’s not gender- or ethnic-specific.” Which is how it ended up getting interpreted by downtown performance mainstay Jim Findlay, a biker-sized hulk of a man from whose mouth both Lee’s narration and songs sounded so different, she said, that “I completely forgot I ever said them.”

In developing the show, Lee found the meeting of minds between her and her band, Future Wife (with whom she has recorded an album of the We’re Gonna Die songs, and with whom she plans to tour as a bona fide rock band outside of theatre venues) natural and complementary. “I feel like rock people are very theatrical, and theatrical people are rock-and-roll—there’s a lot of similarities.” Or, as Stew memorably put it, “I have learned that a great actor can do anything, even sing. Certainly sing in a rock band. A great actor maybe can’t necessarily sing Oklahoma!, but a great actor can sing any song of mine. I’m convinced of it, because I’m not a great singer either, but I buy the songs I’m singing, and I sell it. I’ve seen actors who literally don’t have singer on their résumé kill on our songs.”

There’s some precedent for the band-musical form, and for its replicability. Pump Boys and Dinettes trucked to Broadway in 1982 featuring its original cast of writer/musician/actors, and has since been restaged all over the world, including in a long sit-down run in Chicago. (A Broadway revival helmed by John Doyle was slated for this month, but was scuttled, with the producers citing an overcrowded season.) In the case of last year’s Tony winner for best musical, the yearny folk romance Once, songwriters Hansard and Irglová—who appeared more or less as themselves in the scruffy, lovable 2006 independent film—aren’t in the stage show at all. But the musical’s considerable appeal has much to do with the show’s intimate sound world, forged by an estimable ensemble of 12 actors/musicians.

Martin Lowe, who won a Tony for orchestrating the guitar-heavy, Irish-folk-inflected score, described his job as more analogous to producing a record than to traditional notation. “I transcribed the songs as best as I could from the soundtrack recordings,” said Lowe from London, where he’s preparing the show’s U.K. debut with director John Tiffany and playwright Enda Walsh. “Then I went into the rehearsal room, and I didn’t throw those parts away, exactly, but this was a company of extraordinary people. They’d say, ‘I’d love to play mandolin in this song,’ or, ‘I’ve brought my ukulele in today.’ There was a lot of experimentation; they own those arrangements.”

“At this point, it’s the greatest band I’ve ever played with,” gushed Lucas Papaelias, a seasoned actor/musician who plays guitar, mandolin, banjo and drums—as well as the part of a rowdy Czech immigrant—in the Once ensemble, and who said he came up with his own parts for much of the music onstage, in the time-honored collaborative way of bands from folk to rock to jazz. His high praise for the Once troupe, which has gigged together as a band outside their Broadway job, is saying something: Papaelias is a veteran of New York’s rock club scene and a writer/performer of hybrid shows himself (Ithaca, Pyramidica). He knows as well as anyone what bands can bring to the stage.

“Being in any musical relationship is the trickiest, most intense relationship you can have,” said Papaelias. “When you go see a band that’s starting to blow up, that you get in on the ground floor with, you feel the energy. A lot of that energy has to do with the fact that they even exist, that they’ve even been able to keep their shit together and not kill each other.”

The theatre, Papaelias said, can harness and hone that energy.

“The theatre offers a structure, the world of how you rehearse, of telling a story—all of the stuff that is set up that you don’t normally have as a musician or a band,” said Papaelias. Alvarez agreed: “There’s such a code of collaboration in the theatre; even people who don’t know each other can immediately access this code and create functional—and sometimes dysfunctional—working relationships.” By contrast, in music, “There’s no code, and all the drama in bands is treated with such horror—there’s a lot more blindness about how you manage collaboration.”

Another attraction of theatre work for musicians is that it gets them off the touring treadmill. After playing as many as 150 shows a year, Groovelily’s drummer Lewin recalled, “The first time we did our show in Philadelphia, I went in on the second day of rehearsal and all of our gear was still there. It was like a mirage. You mean my drums are here and we don’t have to set up anything?”

Stage work provides not just freedom from hassle, but a freedom to realize creative ambitions that may feel out of reach amid the grind of recording and going on the road.

“A lot of artists have felt the fatigue that what used to work doesn’t work anymore,” said Alvarez. “We’re looking for, in a way, an escape hatch so we can be artists to the fullest degree that we’ve ever been able to. Also we’re getting involved in something that’s more sustainable and that’s more kind to our art, you know?”

That’s the thinking behind the Joe’s Pub commissioning program, said Thake. “With the collapse of the music industry, the idea of having a career as a musician is rapidly evaporating. So what are tools we can give artists? The live show is king. You have to have a good live show; if you don’t, you’re in real trouble. And even if you have a live show, you can’t have a life—you have to constantly be on the road.”

Settling down into a creative marriage doesn’t guarantee a nonstop honeymoon, of course. If there’s a short trip between writing and trying out material with a band, there are few shortcuts to polishing a work for the stage. The banjo-playing troubadour Abigail Washburn is learning that with Post-American Girl, a show about her travels to China, which recently premiered at Joe’s Pub. Though she had the help of director Meiyin Wang and Chinese Theatre Works, the playwriting ball was in her court.

“I’m used to being a storyteller in my songs, but not of a larger story,” Washburn confessed. “I’m even having trouble calling it a play—I’m not a playwright. I’ll call it a ‘stage piece.’”

Said Stew, “Music isn’t hard for us, but writing those plays is hard, and it’s time-consuming. Every playwright who’s reading this will know that, if you take the commission you get and divide it by the amount of time you take writing the play—we should be delivering pizza.”

And though Stew and Rodewald have had the support of producing theatres to develop their work in roughly the way bands jam through to a great set, that isn’t always an easy model to replicate. Kyle Jarrow, a theatre composer and bandleader best known for A Very Merry Unauthorized Children’s Scientology Pageant and Hostage Song, created a stage piece called Raptured with his band Sky-Pony last year, under the auspices of the New York–based Play Company. The workshop production went well, he said, but the next step was hard to figure out.

“The Play Company thought, ‘Why don’t we send you to one of the summer musical theatre workshops?’” recalled Jarrow, a wiry, casually intense icon of geek chic. “But it’s not feasible to bring eight people and all of their equipment to develop a show in a room. Theatre producers aren’t used to that kind of budget.”

That’s just the writing and rehearsal phase; there’s also the non-trivial question of the performance space itself. As Malloy put it, “Theatrical venues have all these trappings that are so bad for music—they’re the antithesis of the musical experience. The politeness, the seats, you can’t have drink or food in there, the quiet.” He cited another show in which he wrote and performed, Banana Bag & Bodice’s Beowulf: A Thousand Years of Baggage, which toured Australia’s Adelaide Festival last month and will run at ART’s Club Oberon April 16–May 5. “I feel like our best Beowulf shows have been in rock clubs. That’s where this work should be happening; there just aren’t a lot of those venues.”

For Natasha, Malloy and director Rachel Chavkin transformed Ars Nova’s modular space into a supper club, and their goal for the remount was to customize a venue where the show could run for a while. “There just isn’t a theatre we could move into with that show, and there’s no existing bar or nightclub, because they already have a different act in every night, that can host full runs.”

Club Oberon isn’t the only place in Boston where theatre and music are meeting in new ways. Jason Slavick’s company Liars & Believers is all about blurring the lines between stage show and rock show. Last year he helped the band Walter Sickert & the Army of Broken Toys transform a concept album into a scripted show called 28 Seeds at the Boston Center for the Arts. In May he’ll produce Icarus, another hybrid piece, by local composer/performer Nathan Leigh. Though he’s also an old-school straight theatre fan himself, Slavick is driven, he said, by the all-too-familiar search for young and engaged audiences.

“At most plays I go to, I’m the youngest person in the audience,” noted Slavick. “But I go to rock shows, experimental art shows, performance art shows, and the audience is in their late teens and twenties. There’s a kind of immediacy of experience with musicians and sound that speaks to that audience. This is a generation of people who say, ‘I don’t go to theatre,’ but they’ll go to a weird-ass fuckin’ thing if there’s a live band and it’s $15.”

In Texas, Houston’s Catastrophic Theatre has been cross-breeding its own musical mutants with some success. Artistic director Jason Nodler has thus far created two shows around the songs of outsider artist Daniel Johnston (Speeding Motorcycle and Life Is Happy and Sad), as well as the multilayered Bluefinger, after the Black Francis concept album inspired by Dutch art-rocker Herman Brood. Said Nodler, who employs local bands and musicians as much or more than trained actors: “I love music more than I do theatre. The kind of work that interests me doesn’t exist unless I do it.”

The future of musical theatre may rest with artists who don’t think of it as crossing over to play music in their shows, or to put some theatre in their music. PigPen Theatre Company, a troupe of seven Carnegie Mellon theatre grads, has created a homespun ensemble aesthetic involving folktales, funny accents, shadow puppetry—and rousing live acoustic music that handily lives up to the inevitable Mumford & Sons comparisons. Like Young Jean Lee, they’ve released an album (Bremen) and are embarking on a tour of music venues, quite apart from their shows for theatre, which includes The Old Man and the Old Moon, that had an Off-Broadway run earlier this year and will sit down at Chicago’s Writers’ Theatre this coming fall.

“As we’re hitting the road as a band, this record company guy we know asked us, ‘In the future, do you see yourselves theatricalizing your concerts?’” said PigPen member Arya Shahi. “It’s just so funny that both industries are trying to break into each other. We’re getting asked the same questions on opposite ends: Do we think of ourselves as a theatre company that plays a lot of music in our shows, or do we think of ourselves as a band that has very theatricalized concerts?”

Thinking of bands as musical-devising ensembles may be one way that institutional theatres, some of whom have already taken the plunge in commissioning group-developed work, can get their heads (and their producing budgets) around this hybrid form. It’s also a connection that effectively reboots a deep affinity, according to Stew.

“I pay theatre the highest compliment,” said Stew. “As much as I worship music, I think music is theatre. I think any time you’re doing it in front of somebody, it’s theatre.” He cites a moment in The Total Bent when, in the middle of a song, a character who hasn’t played an instrument before walks over to a drum kit and kicks it into high gear. “It electrifies the house. It’s like, ‘Oh my God, this is actually happening!’ You couldn’t write that.”

Has a good beat, though. You might dance to it.