“Brave” is a word sorely overused by critics when describing any actor taking on a somewhat sexualized character – especially when they take off their clothing in the process. If the sexuality in question is LGBT, so much the “braver,” apparently. It’s a word, then, that you may have read applied a few times to Robin Weigert’s terrific performance as a dissatisfied lesbian wife and mother in Stacie Passon’s sharp, sensual debut feature “Concussion” – released last Friday on the Weinsteins’ TWC-Radius label.

Among its many individual merits as a witty, pointed study of normalized alternative families and the long-haul challenges of homosexual domestic bliss, “Concussion” also delights as an overdue leading-lady showcase for Weigert – the warm but tough-as-nails character actress whose strongest career opportunities to date have been on the small screen. She received in Emmy nomination in 2004 for her vitally vulgar Calamity Jane in cult Western series “Deadwood,” and is regularly featured in the hit biker drama “Sons of Anarchy.”

Until now, Weigert’s most generous film opportunity came in Steven Soderbergh’s odd stylistic experiment “The Good German.” That has now been handily bettered by complex, prickly role in “Concussion” as Abby, a woman who handles the combination of familiar suburban ennui and spousal indifference in a rather unexpected fashion: she takes up a secret occupation as a high-end call girl in New York City, serving other women with unfulfilled sexual needs.

The character has stoked controversy since the film’s divisive Sundance debut, but Weigert plays her with weary good humor, casually blossoming as Abby grows more comfortable in her imperfect skin. If it is indeed a brave performance, it’s not self-consciously so.

“I don’t really know how I respond to that word,” Weigert says breezily on the phone from New York, where she’s spending a few days before heading to Nebraska to complete work on a “beautifully surprising” film project. “I mean, yeah, it does put you out there, literally and figuratively, when you are playing a character who has a lot of sex on screen. I don’t know that it matters what type of sex. I think when I feel fear, that’s often a cue that I should do something. If I begin to feel fear, that’s a strong sign, psychologically, that something has its hooks in me somewhere deep. That’s why we do it.”

A large part of Weigert’s fear didn’t stem simply from her character, but the prospect of taking on such sensitive material with a first-time feature director. Weigert didn’t pursue or even audition for the role; instead, she was somewhat bemused when Passon approached her out of the blue.

“For whatever reason, Stacie saw me as this character,” Weigert says. Even now, she still sounds surprised. “I don’t know what in my previous work suggested this role to her, because I have done a lot of character parts and I don’t see anything in my body of work that exactly resembles this character, but she somehow Abby in me. That was my great fortune.”

Flattered as she was, Weigert admits to having some reservations before finally taking on the role. “I might have backed away from it, if it hadn’t so taken hold of my imagination,” she says. “It scared me, because I couldn’t really look to seven other movies Stacie had made and say, ‘Okay, I know what this will be.’ It felt like it could turn out to be anything. But something about this journey of a woman back into her body, from a dissociated state back into something that she had probably left for dead – that spoke to me.”

Once on board, however, Weigert got actively involved in the project beyond her own remit as a performer – recruiting a number of friends and colleagues to join her on the challenging endeavor. Most notable among them is her “Sons of Anarchy” co-star Maggie Siff, who shines in tangy supporting role as one of Abby’s most unlikely clients.

“Once I was in, I was determined that it needed to be of good quality, that the cast was full of people I could rely on,” says Weigert. “That made me feel more secure. But once you’ve committed, you just go blind, and you go all the way, and then you hope. Because there really isn’t any kind of guarantee that it’s going to work.”

This wasn’t the first time Weigert had undressed on screen, though her previous experience in this area was markedly different. “In ‘Deadwood,’ it was just extremely unaesthetic,” she laughs. “They actually put underarm merkins on and covered me with dirt! So it wasn’t exactly in a sexual context. I’ve played a couple of strippers – including in ‘The Good German’ – but it’s brief, it’s light. This was definitely new to me.”

Weigert was additionally concerned that Abbie was too chilly a presence to carry audiences through the film: “She sits at such a cool temperature for the whole first part of the film, I wondered if an audience could join her. She’s so relatively dissociated, which is partly head injury-related and partly from finally waking up to this stultifying existence of hers. That was where I really had to trust Stacie, who had a very clear vision for that first third of the film, and that character.”

For her part, Weigert found her way into Abby via such physical details as the character’s grueling exercise and diet regimen, which the actress herself faithfully followed. It’s a lifestyle that the film cuttingly satirizes, opening as it does to a montage of blank-gazed suburbanites at the gym, set with winking irony to Bowie’s “Oh, You Pretty Things.”

“Doing that to yourself concertedly for a period of time makes you feel a bit like a gerbil in a treadmill: the world goes a bit gray,” she muses. “You’re probably getting healthier, but it’s repetitive, and somewhat empty. I did that for a couple months. It wasn’t planned that it would have as much of a psychological effect as it did. But I think that was part of how I married this particular character. “

She continues: “It’s such an obedient way to be for a woman, to try to keep yourself in top shape, to follow all the rules and hope that will get you a measure of stability or happiness. That’s part of the affluent suburban dream: to do everything perfectly in a long-winded way, to try to fulfill all the requirements. So it started with that and then it evolved into something that felt almost chemical.

“One of the things that is interesting about the movie is that the role I occupy in the film is typically a masculine role. The one who is not satisfied sexually. But making it two women shines a different kind of light on it. I suppose it allows an empathy that might be short-circuited by saying, ‘Oh God, yeah, all men are that way. Isn’t this always the way?’”

Weigert had a small role last year’s Sundance hit “The Sessions,” and regards that very different sexually-themed character drama as an unlikely reference point for this one – and not just because of her admiration for Helen Hunt’s Oscar-nominated performance as an uninhibited sex surrogate. (“She’s a very shy actress by nature,” she says, “and was so gracious in handling that intimacy and exposure.”)

“Surrogacy is obviously a world away from prostitution,” she says, “but still, she doesn’t render herself the object; she very much remains the subject as she takes on these clients. I imagine that in this way Abby can have what she needs to feel alive, and can also maintain the life that she has with her wife and children. It’s misguided and not generally realistic, but I think I can understand where that thinking might come from.”

Though “Concussion” proved something of a revelatory career turn both for the actress and her admirers, Weigert has no plans of abandoning TV for film: she recently played a small part on a 10-part experimental series by Neil LaBute, and has landed a role in an upcoming series pilot opposite Philip Seymour Hoffman.

“Television has changed,” she says approvingly. “Some feels like good old-fashioned TV, and some of it feels more filmic and more natural and more nuanced. I don’t think there’s any clear line any longer between film and TV. Something like ‘Deadwood’ was much more of a film-like experience, in terms of the time that was spent. I kept going to other television shows and wondering, ‘Why isn’t this experience more like ‘Deadwood?’ Why are we in such a rush to get this done?’”

In the meantime, Weigert is palpably excited about the new feature she’s working on, another effort from a first-time filmmaker that she describes as giving her the same positive jitters “Concussion” did. There’s nothing sexual about this role, she explains, “but there’s a lot of my mother in there, and when you know you’re going to be mucking around in those waters, that’s a little scary too.”