Alterna-country, like high-concept and military intelligence, is a term that means its opposite. The label is applied to what’s essentially authentic country music, a style based in rural American tradition, driven by heart, and dealing with real-life issues in an uncontrived, personal manner. It’s a style meant to be relevant longer than the next quarterly shareholders’ statement. And by that definition, no other musician is making better honest-to-God country music today than Dolly Parton, who plays the Lowell Memorial Auditorium this Wednesday. Who would have guessed 25 years ago, when her first platinum hit, "Here You Come Again," was ushering in the so-called "countrypolitan" sound, that Parton would return to her Locust Ridge (Tennessee) roots and evoke the spirits and passions that echoed in the boilerplate recordings of the Carter Family, Jimmie Rodgers, Hank Williams, and Bill Monroe . . . and toss in a little Led Zeppelin, too?

That’s been the game plan for her last three albums, 1999’s The Grass Is Blue, last year’s Little Sparrow, and her just-released Halos & Horns, all on the bluegrass-and-folk-inclined Sugar Hill label. The first two are gems that romance the bluegrass and Appalachian music Parton first heard as a child and devoured so prodigiously that she was ready for her Grand Ole Opry debut in 1958, when she was just 12. Little Sparrow, in particular, captures the storm clouds of fable that hang over the Smoky Mountain hamlets of her raising, with its tales of witches and star-crossed lovers and the pervasive sense of sweet, sad loss in her pure-toned voice, which rings true as Monroe’s high-and-lonesome call.

The playing on both albums is impeccable, as it is on Halos & Horns. Parton, who produced the new CD, hand-picked an ensemble whose quick-stepping ability to integrate dobros, mandolins, banjos, acoustic guitars, fiddles, and bass might be considered reckless if not for the Navajo-blanket precision of the lovely arrangements. There’s breathing room for all, with almost every instrument stepping to the fore — often within each number — and then sidling back into the mix without a ripple.

Of course, most of the room is reserved for Parton’s magnificent, octave-leaping instrument and her tight gospel chorus of backing singers. Notwithstanding that she’s 56, her voice seems only richer and less predictable. The biggest surprise is her impersonation of an aged mountain crone in "These Old Bones," where she employs a voice inspired by her mother’s dry, flat twang. Actually Parton sings two roles: the wizened seer and healer and the young woman to whom the older one passes her gifts. The story is a nice metaphor for what Parton has done with this string of albums — carrying the unfiltered musical notions of the past into the present, for the benefit of another generation.

Halos & Horns’ best songs are written by Parton. They include the portrait of depression "Not for Me," the charming country romance "Sugar Hill," and the title track, in which she grapples with the conflicts between innocence and experience like a down-home William Blake. But the tunes likely to get the most attention are the covers. For the third time she’s translated pop hits into the language of Locust Ridge. On The Grass Is Blue, she delivered a scaldingly quick flash through Billy Joel’s "Travelin’ Prayer." Little Sparrow found her tweaking Gershwin’s "I Get a Kick Out of You." This time there’s Bread’s "If" and Led Zeppelin’s "Stairway to Heaven." The former is, alas, still treacly, but "Stairway" ends the album, just as it’s ended thousands of high-school dances.

And inn Parton’s hands, it’s a work of precise beauty. Banjo and mandolin blend arpeggiated rhythms as lush, slow-paced violin and dobro sail on gentle melodies — all just below the skipping tones of her voice, which slowly forms each note into a cotton-candy delicacy. Parton changes a few choice words as she heads for the rave-up finale, replacing the ambiguity of Robert Plant & Jimmy Page’s lyrics with a morality play that points toward redemption’s road. The big ending starts with a flourish of dobro and violin, but the soloing gives way to Dolly and her choir, the latter pumping church-style behind her vocal testimony to the emptiness of Mammon. It’s a gas with enough showy virtuosity to stand up to ol’ Pagey’s guitar rip.

Given her track record of films, songwriting triumphs (she penned the Whitney Houston mega-hit "I Will Always Love You"), theme-park development, and wide-ranging recordings, it’s hard to predict where Parton’s interests will take her next. But for now, Halos & Horns, Little Sparrow, and The Grass Is Blue make the case for her coronation as country music’s modern-day queen.

Dolly Parton plays the Lowell Memorial Auditorium this Wednesday, August 21, at 8 p.m. Call (617) 931-2000.