Julia Roberts laughs with host David Letterman on the set of the "Late Show with David Letterman" on Tuesday.
Julia Roberts laughs with host David Letterman on the set of the “Late Show with David Letterman” on Tuesday.

HOLLYWOOD — The word layoff has an entirely different meaning for a Hollywood movie star than, say, a fired GM worker, but both involve career idleness, apprehension and questions: Is Julia Roberts’ new movie, “Duplicity,” a thriller or a comedy?

More intriguingly, can it restore the woman who was or perhaps is the queen of the screen to the luster she once enjoyed as the $20 million-a-picture heavyweight box-office champion and mistress of all she surveys?

It would be nice to think Roberts didn’t care about fame. And maybe she doesn’t.

In Hollywood — the concept, not the location — months can be lifetimes, years can be eons. Having carried three children since she last had to carry a picture (“Mona Lisa Smile” in 2003), Roberts has delivered vocal performances in the animated “Charlotte’s Web” and “The Ant Bully” and reprised a relatively minor role, as Tess Ocean in “Ocean’s Twelve.”

She also has managed to star in a Broadway play, “Three Days of Rain,” which was hit by a critical Katrina and floated away after 70 performances.

And she has been a member of forgettable ensemble casts in “Closer” (2004) and last year’s German-made “Fireflies in the Garden” (which opens in the United States in June, maybe, having already opened and closed all over the world).

For an actress who has never really been required to act, the one recent bright spot was “Charlie Wilson’s War,” a commercially mishandled gem. Roberts gave a spot-on performance as a Republican crypto-fascist Texas socialite who worked toward saving Afghanistan from the Russians, when not bedding Tom Hanks’ congressman, Charlie Wilson.

It certainly wasn’t “Sleeping With the Enemy.” But the movie did less business than a Taliban liquor store.

All of which leads to two conclusions: Julia Roberts has been doing what she wants. And Julia Roberts is a gamble. This is not something anyone ever thought they’d be saying — not anyone cinema-conscious from 1988 (“Mystic Pizza”) through, say, 2000 (“Erin Brockovich”).

But the romantic-heist movie “Duplicity” — in which she and “Closer” co-star Clive Owen play ex-spies who may or may not be in love — has been kept under wraps by its studio, which doesn’t seem quite sure what it is. (It opens Friday.)

It’s hard to believe that Roberts suffered an Oscar jinx once she got her statuette, for playing a real-life heroine in “Brockovich,” but there hasn’t been a movie since then that would be mentioned in the first 10 paragraphs of any Roberts obituary. … Even though, arguably, she’s done some of her better work since.

What she hasn’t been doing is being a movie star, which is why Julia Roberts matters. No? Consider that Roberts was virtually the only female film star, for years, who possessed the commercial potential her elder sister stars held in the 1940s, which means they ruled. As movies of the two past decades became more and more the purview of sweaty monosyllabic he-men, Roberts conquered mini-genre after mini-genre.

Building on the mega-celebrity of “Pretty Woman,” she did brief duty as the imperiled victim (in “Sleeping With the Enemy,” which is pretty unwatchable now) before she started playing women of self-possession and spunk.

And audiences agreed silently to excuse the most ludicrous stories for a chance to see her: “The Pelican Brief,” “I Love Trouble,” the gothic-revisionist “Mary Reilly” and “Conspiracy Theory” with Mel Gibson, one of her better matchups. (Steven Spielberg thanks us for stepping over “Hook,” and let’s also forget Robert Altman’s lugubrious “Pret-a-Porter”).

Was any of this memorable, I-have-to-watch-it-again-type stuff? Well, Gibson going ga-ga in “Conspiracy Theory” was kind of fun. But no: For all the gelt she raked in, Roberts wasn’t making indelible movies.

Yet, there have been moments that suggest that as Roberts ages out of glamorhood — she’s 41, the camera can be cruel and Hollywood has an unyielding obsession with the vacuously pretty — that Roberts will become something more than a sex symbol. One of her assets is generosity, actorly generosity, which can work in a performer’s favor.

An early example was “Stepmom” (1998), in which she had the unenviable job of making Ed Harris’ second wife sympathetic while his first, played by the not-always-subtle Susan Sarandon, died of cancer. Fast-forwarding to “Mona Lisa Smile,” she gave elbow room to three gifted and younger actresses (Julia Stiles, Kirsten Dunst and Maggie Gyllenhaal) and made herself look good in the process (despite the movie characters’ tendency to be anachronistically enlightened).

In the largely forgotten “America’s Sweethearts,” Roberts played second banana to Catherine Zeta-Jones and stole the show. And in “Notting Hill,” she played a character who was essentially Julia Roberts, while allowing Hugh Grant to do his charmingly bemused shtick unfettered.

Then there has been Roberts’ association with Steven Soderbergh, which has ranged from the slickly comedic (and seductive) “Ocean’s Eleven” and “Twelve” as well as his “Full Frontal,” one of the director’s periodic forays into experimental cinema that would never have gotten any attention without Roberts’ participation.

Likewise, she helped out pal George Clooney by playing the mystery woman in his directorial debut, the oh-so-memorable “Confessions of a Dangerous Mind,” in which she was first-rate.

“Charlie Wilson’s War” wouldn’t have been the same without her, all of which sets up the predictable declaration that American movies haven’t been the same without Roberts.

But nothing’s ever the same at the movies, except the ravages of time, and the risks involved when you make yourself scarce.