There's a few things the title of the new ZZ Top album, X X X, can stand for. It could be for a particular kind of movie rating; maybe that's why Billy F Gibbons, Dusty Hill and Frank Beard offer a conspiratorial, communal leer when that possibility is raised.

It may be a nod to Dos Equis beer, one of the trio's favorite brews.

Or it might signify the 30 years "that little ol' band from Texas" has been together. "We're allowing that confusion to remain," Gibbons says of the mysterious and ambiguous title. "The truth is, nobody quite knows what the expected meaning was to be."

Suffice to say that whatever you call it, X X X is the latest offering from a band that doesn't have to explain itself -- but, rather, has done just that through three decades of varied and adventurous music making, a far more ambitious path than you'd ever expect from a guitar, bass and drums trio.

What IS ZZ Top? It's blues and rock. Texas and Memphis. Grit and grins. Cheap sunglasses and sharp-dressed men. Gorgeous women and fast cars -- or is that gorgeous cars and fast... well, you get the idea. But inside it all is a sound and an attitude that's sold millions of records, a combination of Gibbons' pesos-plucked guitar, Hill's rumbling bass and beardless Beard's deceptively sly rhythms.

"I guess we could attempt singing all sorts of styles of music," Gibbons notes, "but nothing really gets too far away from being identifiable as 'Oh, there's ZZ Top. There's some elements that remain that make it identifiable as 'those three bearded boys."

Those elements are there in abundance on X X X, which has all the winking humor and musical gutsiness of its 12 predecessors. Originally conceived as a live album, X X X combines eight new studio tracks with four live selections, a blend that worked so well on 1975's "Fandango!" The concert tracks come from unannounced surprise club shows around the country. The studio tracks, meanwhile, were cut mostly in the trio's natural progression following the back-to-basics exercise of 1996's "Rhythmeen."

"I thought that 'Rhythmeen' really re-established to the fans who were curious if ZZ Top still has a piece of that just pure trio left," Gibbons explains. " (X X X) is perhaps a little more accurate to the tradition of what ZZ Top has done on most of the other records, and that's pushed and pulled at whatever might add to a sound. There's drum loops and even some synthesizer parts show up -- things that we haven't done in awhile but are nonetheless valid and legitimate studio exercises."

Of course, like most ZZ Top albums, X X X is not to be picked apart and analyzed. Rather, it's to be consumed and enjoyed as a piece, from the sizzling licks of "Poke Chop Sandwich" -- an homage of sorts to blues great Lightnin' Hopkins and his drummer Spider, who kept a pork chop sandwich on his kit -- to the barroom blitz of "Fearless Boogie," the hubba-hubba grind of "36-22-36," the psychedelic overtones of "Trippin' " and the sonic odyssey of "Dreadmonboogaloo," a salute to nocturnal DJ Art "Senor Saucer" Bell, whose radio program often escorted the Top boys home from sessions in the wee hours shortly before dawn.

On the live side, we have "Sinpusher," a variation of the "Antenna" album's "Pincushion" because "one night we played it and forgot the words, and we liked this one better," Gibbons says. We're also graced with the Hill-sung blues take of "(Let Me Be Your) Teddy Bear" -- complete with a "lost" verse. And those listening closely to "Hey Mr. Millionaire" can hear a rare vocal performance by guitar great Jeff Beck, a ZZ buddy who hunkered down with Gibbons in a Dallas hotel to rekindle the spirit of mutual favorite Robert Johnson.

All told, X X X shows ZZ Top is entering its fourth decade in fine form, another stunning accomplishment to join the list that includes -- in no particular order -- the now historic Worldwide Texas Tour, countless gold and platinum albums, a new RIAA Diamond Award for selling more than 10 million copies of the "Eliminator" album, MTV Video Music Awards, a halftime performance at Super Bowl XXXI, honors from seemingly every politician in Texas (free chicken dinners, folks...) and, perhaps most importantly, the group's heartfelt patronage of the Delta Blues Museum in Clarksdale, Miss.

And the best news is that there's no sign -- praise the lord -- of stopping any time soon.

"We still enjoy playing together," Gibbons says. "And as a band, that means a lot, if not everything, in this unified pursuit of the collective unknown. I don't know of anything that we have more fun doing. In fact, we've been in this band longer than marriage, longer than school, longer than anything we've ever done. And it doesn't seem like 30 years, either."