One suspects it’s rare for Nadav Lapid to crack a smile, but a sly one crosses his face as he describes what it’s been like to see the reactions to his latest film “Synonyms” since it took the world by storm after its premiere earlier this year at the Berlin Film Festival.

“I’m a very pessimistic person and very often, I feel like nobody cares about nothing anymore,” says Lapid, allowing himself a grin recently during the Toronto Film Festival. “When people care, it’s great.”

It is Lapid’s considerable gift to break an audience of their apathy and he seems to be delighted as much, if not more, by those who have left “Synonyms” angry as have enjoyed it, with some considering it to be among the decade’s best films. While opinions may vary, what can be agreed upon is how the director of “Policeman” and “The Kindergarten Teacher” has constructed another cinematic equivalent of a Molotov cocktail that’s bound to leave an audience shaken, for better or worse. From its arresting opening scene in which you meet Yoav (Tom Mercier) as bare naked as the day he was born, running around in a panic around an apartment in France you’re unsure belongs to him, “Synonyms” grabs you and refuses to let go even after the end credits start to roll, telling the story of an Israeli expat who has resettled in Paris following the nationally-mandated tour of duty in the military.

Yoav eventually puts on some clothes, offered help by Emilie (Quentin Dolmaire) and Caroline (Louise Chevillotte), a young, carefree couple that lives in the building, but they can only fit so well when he’s never entirely comfortable in his own skin as nasty memories of his time in the service course through his mind like coming across thorns on a vine and he relies on a French-Hebrew dictionary to translate his thoughts into abstract approximations of what he actually wants to say. When words fail, Yoav expresses himself through action, which is convenient for finding work at the Israeli embassy where he’s hired for his muscle, but apt to destroy everything in his path as a force of nature that can hardly be contained, both confused and upset when he feels used and alienated from the country of his birth and unable to settle in his new home as Emilie and Caroline begin making demands of him as well.

Although Yoav is doomed to only be able to share a fraction of what he’s really feeling with those around him, Lapid conveys the dizzying experience of being inside his mind in exhilarating fashion, taking a feeling that he once had himself and making it personal for anyone who’s felt like an outsider. It’s an extraordinary film that arrived on American shores this week after a torrid international run on the festival circuit and Lapid spoke about his most autobiographical film to date, finding a fearless actor to play the lead and how the idea of a thesaurus came into play.

Why was this the right time for you to tell this story?

What makes it good timing is the fact that it’s still vivid. [These] things happened maybe 16, 17 years ago, but luckily — or unluckily, I guess — the questions still aren’t solved, apart maybe from hitting or pounding a closed door or something like this, and maybe with a certain perspective of time, I can analyze it a bit and I can make some observation. But it’s still vibrant, and maybe it became even more urgent because when these dilemmas aren’t solved, they accumulate a certain volume and maybe what I feel or what I see is the Israeli sickness is growing and growing. So this is one thing, and the second may be more practical, but when all of this happened, I had no idea what I’m going to do with my life. I wasn’t thinking about films in particular. I wasn’t such a cinephile and my notion of cinema was very basic. I was writing novels, thinking I’m a writer, but when all of this took place in reality, I took some notes without even knowing why or what I was going to do with them. I just felt that something is happening.

So I took some notes – some were dry descriptions of events and some of them were an attempt to detail certain feelings – and then life advanced and I went back to Israel and started [making] cinema. I had a graduation film called “Emilie’s Girlfriend” that was in Cannes in 2006 that in a way is the second part of “Synonyms.” It’s exactly the same [central] characters of Yoav, Emile and Emile’s girlfriend, but in this film her name is Delphine, and [in “Synonyms”] she became Caroline. But it takes place two years after Yoav went back to Israel. [Back then] I couldn’t imagine back then that someone would be interested in letting me shoot in Paris, so I started making my [other] movies – “Policeman” and “Kindergarten Teacher” – and I started to get a lot of demand from French producers, asking me if I had an idea for a film that takes place in Paris. One of them invited me to come to Paris for a meeting and I didn’t have any idea – I was inventing stupid scripts. [laughs] And while going to the meeting, I suddenly told myself, “Actually, there’s a very, very fundamental and essential thing that took place in Paris, so why not go into the truth?” And this was the beginning.

The film uses time in an interesting way – it takes place in the present tense, but there’s voiceover as if he’s reflecting on this time from the future and there’s abstract flashbacks. How did you want that to work?

I think that more time passes, the more I become a fan of what I feel is the deepest naked truth of things and I try not to let practical things stand in the way of the movie. The truth of this is it took place in the past, but it’s still happening, so it still belongs in a way to the present. It’s a continuous historical film, so that’s why in a way I gave hint to [the past] or I refer to it, while putting this voiceover that talks about it as if it’s something that took place in the past, but the film is very existential in taking place in the present. And people say the film is unpredictable, but I feel from the first moment, it’s classical [structure] and not classical. It’s classical because the guy arrives and you know that he will leave. It’s a little bit like “Barry Lyndon.” It begins with a guy from a simple background who arrives to nobility to live this dream of nobility, only to go back accompanied with the same musical theme back to his poor background. So in a way, the drama here isn’t what will happen, but how will it happen and what you will feel when it happens, and by integrating this [sense of time] in early stages of the movie, I felt that in a way I’m focusing the drama on the how and the intensity of existence and not on the narrative question of what will happen.

You’ve said movement is something that was integral to figuring out this story. How early in the process are you thinking about it?

When I decided to make the movie, pretty early I understood that my success depends on recreated the passion because the guy is in permanent movement, and the movie is a little bit of battle between mobility and immobility. For instance, Emile and Caroline [contribute] to the immobility and Yoav has to be a real warrior all the time because he’s fighting against the actual moment and its boundaries, which means when you wait for him inside, he will be outside. When you wait for him to sing, he’ll keep quiet. When you wait for him to shout, he’ll whisper. He’ll talk normally and then suddenly, he’ll shout and dance. Also, if you ask him what’s his problem with Israel, he could speak to you in all the negative synonyms he could find in the French dictionary, but he won’t be able to give a precise argument.

People ask me if he [suffers from post-traumatic stress disorder] and I say maybe he’s post-traumatized, but then his trauma is life, and it’s because it’s not based on an argument, it’s based on passion. Passion is movement and the movement is going nowhere because it’s like he wants to be Napoleon, but at the end, he’s walking and mumbling synonyms. There’s also something dynamic in synonyms because the word moves from this [word] to [another], and on a list of synonyms, the first one is the closest [to the original meaning] and the more the synonym is advanced, the more distance is created with the original words, so this is the key thing for him.

What sold you on Tom to play this guy?

It’s a lot of things. First of all, Tom began his career as the youth Judo champion of Israel and everyone predicted he’d win gold medals in the Olympic games and from one day to another, he abandoned this and became a dancer, so I think all of [Yoav’s contradictions] exist inside him, meaning that he’s extremely sensitive, fragile, tender, nice, polite, and hard working and at the same time, there’s a lot of violence and irrational rage you feel he can expose at each second. He’s totally limitless. And there are these [movie] stars who are stars because they don’t care about anything and they’re completely egomaniacal. Tom is not like this. He’s extremely humble, but he doesn’t know that limits exist in the universe. For him, playing naked or playing with clothes or doing this or that, it’s doing exactly the same thing, so it really is the character.

Of course, today, it’s not really possible to separate him from the character [now] because it’s so connected. Honestly, when I started to cast the movie, I had a slightly melancholic feeling because I imagined myself in the movie because it’s based on true events, and when I was writing the script, I imagined myself 17 years ago and after the casting, it was like I don’t exist anymore. The person who passed through all of this doesn’t exist any more and I thought the movie will always be fake. But then I found Tom, and I forgot all of this because I think he was like a better version of myself and he enabled the movie to be a better version of life.

“Synonyms” is now open in New York at the Quad Cinema and will open on November 1st in Los Angeles at the Nuart Theater. A full schedule of theaters and dates is here.