There’s something about the phrase “between the earth and sky” that really works for the Dublin quartet Lankum – which will make its Boston-area debut Jan. 11 at Club Passim in Harvard Square – and not just because that’s the name of their most recent album.

Poetic as the words may sound, there’s a dark context to them: They appear in the last line of the album’s last song, “Willow Garden,” a murder ballad found in the Irish and American folk traditions, and serve as the farewell from the narrator, who’s about to meet his fate on the gallows for brutally killing his sweetheart. (The full couplet is, “They’re going to stretch me up/between the earth and sky.”)

If one wants to get all full-blown analytical about it, the phrase might also suggest a state of limbo, of inhabiting both places yet not fully existing in either, of being and nothingness and all that. It’s the kind of conundrum that seems to suit Lankum, which started out more than 15 years ago as Lynched, an experimental psychedelic folk-punk duo of brothers Ian and Daragh Lynch, and is now one of Ireland’s most popular folk/trad bands – garnering three nominations in the 2016 BBC Folk Music Awards for their first album, “Old Cold Fire.”

Except that Lankum is not your typical Irish folk/trad band. Yes, they draw on the Irish ballad tradition, as well as Irish street or Irish Traveller songs, and the Irish music hall. But the repertoire for Ian (uilleann pipes, concertina, whistle), Daragh (guitar, piano), Radie Peat (concertina, accordions, harmonium) and Cormac Mac Diarmada (fiddle, viola) also includes American folk tradition, plus songs like “Cold Days of February,” by 1960s folk legend Robin Williamson; Johann Esser and Wolfgang Langhoff’s anti-fascist anthem “Peat Bog Soldiers”; and “Drinking Song from the Tomb,” the lyrics by horror fiction writer H.P. Lovecraft. The band’s growing stockpile of original material, meanwhile, includes some tough-minded commentary on a contemporary Ireland struggling with social and economic issues, to say nothing of its very identity.

Complementing this gritty, populist milieu is a sound frequently described as raw and unpolished: instruments and voices (with unapologetic Dublin accents) that don’t always align or resonate smoothly but are mellifluous nonetheless. And Lankum likes to utilize drones and sustained notes from pipes, fiddle, concertina, harmonium, and its not-so-secret weapon, the bayan, a Russian accordion with bass notes that seem to originate in some subterranean chamber – all lending a mesmerizing, almost primal intensity to the music. (For one effect on “Between the Earth and Sky,” they played recordings of pipe drones inside a church, where they recaptured and subsequently enhanced the sound.)

Although often compared with The Pogues or other similar Irish/Celtic groups, Lankum is more deliberative, measured and unhurried, often content to let songs or tunes unfold and reach a climax on their own terms; some tracks can clock in anywhere from seven minutes to almost 12.

So, listening to Lankum can be, in its own way, transcendental: You feel as if you’re simultaneously in a folk music realm and someplace else. And that’s as it should be, says Ian Lynch, who notes that the band’s influences extend well beyond folk and trad to, among other things, ambient music and minimalist composers like Brian Eno.

“What I like about using drones and that kind of ambient sound, especially with older ballads, is they help bring about a different psychic state, one where you’re attuned to the song and what’s happening in it. There are so many distractions in our lives these days, so sometimes it’s not easy to just focus on one thing, but that’s what we go for at our gigs – create a sonic world in which you can lose yourself.

“It seems there’s an idea, an expectation that Irish songs are all upbeat and you play them fast,” he adds. “But if you slow them down, you get a different feeling; more of their inner characteristics come out – pathos, anger, joy, sadness. So our feeling is, you let the song go where it wants, and just let that happen.”

Lynch says he and his band mates are aware of the perception of Lankum as an antithesis of more technically proficient interpretations of Irish music, but they don’t think an awful lot about it. “This isn’t something we consciously put out there. We’re not being critics of performers or bands who strive for that kind of sound. We’re just ourselves, and the kind of music we like – like the music of the Travellers – tends to be on the rough, unpolished side, and to our minds, more emotionally intense. No, we’re not trying to make some kind of point in the way we play; the sounds we make are what make sense to us.”

Above all, Lynch says the band looks to treat the songs from tradition with respect while not being “overly reverent” about them. “You need to enjoy them and make them enjoyable for others. These are not museum pieces that you’re handling with white gloves. If you go in with that mind-set, people will think it’s a recital; you’ve got to engage them, draw them into the story.”

Unlike Peat and Mac Diarmada, the Lynch brothers did not come from a traditional music background. “There was a lot of singing in our family,” says Lynch, “but it wasn’t really traditional Irish – songs from the 1950s and ’60s, popular stuff. Growing up, I might’ve heard The Dubliners, The Pogues, and other acts, so I got that kind of exposure to Irish music.”

Even as they developed and explored their own idiosyncratic music – releasing the album “Where Did We Go Wrong?” in 2004 – the brothers became more intrigued by the Irish tradition: Ian decided he wanted to take up the uilleann pipes, and Daragh refined his guitar-playing and began learning the DADGAD style that is often used for accompaniment in traditional music. The two “went down the rabbit hole,” says Lynch, browsing through archival recordings and materials to build up their knowledge of the music. They also began making the round of sessions, which is how they encountered Peat and Mac Diarmada.

While Irish music might’ve been at the core of the group’s formation, Lynch says the four all felt empowered to integrate their other tastes into the mix. “For me, it’s very important to stay true to our own interests and favorite genres. There’s no point for us to be playing straight-up trad, because we have so many influences to work with. We try to be creative, and use all these disparate ideas and styles.”

As with most bands, Lynched/Lankum took a while to gel, which Lynch feels is a major difference between the first and second albums. “For ‘Old Cold Fire,’ we were drawing mainly on a collection of songs Daragh and I had been doing over the years. But when we were ready to make another album, we had material that all four of us had been working on, so it was really more of a group effort.”

One outcome of the band’s maturation between “Old Cold Fire” and “Between the Earth and Sky” was a more prominent role for Peat as a singer, her commanding voice fitting that rough-beauty dynamic of Lankum. On the latter album, she is the lead vocalist on three tracks (and shares a duet on another), most memorably on the aforementioned “Willow Garden.”

“Between the Earth and Sky” also affirmed the strain of iconoclasticism, and tongue-in-cheek, acerbic, occasionally dark humor in the Lankum persona (they refer to themselves as “Dublin Folk Miscreants”). Having decided that “Lynched” invariably carried connotations of racial violence, the band took on the name of the titular character – a particularly nasty fellow, too – from an old murder ballad. Their repertoire includes pointedly political satire like “Sargeant William Bailey” and “Salonika,” music hall whimsy (“Daffodil Mulligan,” “Father Had a Knife”) and their own “Bad Luck to the Rolling Water,” a parody of sentimental, loved-and-lost Irish songs peppered with hilarious literary and classical references (“She was not Euternatia, nor was she Venus bright/But she could drink much more than you and beat you in a fight”).

The clever turns of phrase have a sharper edge in Lankum originals like “Granite Gaze,” which attacks the religious-based oppression of Irish women and children (“The future’s just a thing we say to keep the sordid past at bay/Still we cling on to the mother who eats her own”), and “Déanta in Éireann,”a modern-day emigration song in the tradition of street ballads that bitterly assesses Ireland’s economic and political betrayals of its people (“For it’s not too late to fight back and these tyrants eject/Take back what’s ours from these primates erect/Our purpose, our lives, and our own self-respect”). And if there were any doubt of the band’s sociopolitical consciousness, it’s swept away by their powerful, respectful a cappella rendition of “Peat Bog Soldiers,” written by Esser and Langhoff while prisoners in a 1930s Nazi concentration camp.

This year will find Lankum back in the studio again, ready to add to a body of work that is possible to examine from its very early years: A link on the Lankum website takes you to all the tracks of “Where Did We Go Wrong?” (including “Sign On,” the brothers’ wicked parody of “Ride On,” the Jimmy McCarthy song popularized by Christy Moore).

“Those songs are a snapshot of where we were at a particular time in our lives,” says Lynch. “It’s not something I’m ashamed of, just all part of our evolution as musicians and singers.”

Maintaining that connection to the past can make for some interesting revelations, adds Lynch: “I got an e-mail a while back from an 18-year-old who had heard our older stuff and enjoyed it, and asked, ‘Where did you go wrong?’ I guess we’ve grown up and gotten soft. I can imagine being that age, though, when the world just seems so black and white. Well, there are so many different grays now.”

Tickets and other information for Lankum’s January 11 concert at Club Passim are available at passim.org. For more, go to lankumdublin.com.