The more complex and important the debate, the more likely a single word can sway public opinion, which in turn exerts irresistible pressure on members of Congress who face the voters again soon enough.

So no matter how much we might agree that the nation’s immigration system is a broken mess in desperate need of reform, one word swells into a Jabba-the-Hut barrier to sensible advancement: amnesty.

It has become almost tiresome to argue over the definition. Supporters, like this newspaper, will point to fact upon fact to show that comprehensive reform is anything but amnesty. Instead of granting guilt-free citizenship, plan after plan requires illegal immigrants to pass background checks, pay fines and back taxes, learn English and start their path to legalization at the back of the line.

Opponents shake their heads and dig in: “They broke the law, didn’t they? Secure the border, and enforce the laws we already have.”

Everyone remains stuck in an angry place that precludes progress toward a smarter, fairer system. It needn’t be this way, and this newspaper is optimistic — for the first time in years — that reasonable people of good intention can push the debate beyond a single nettlesome word.

At some point, those who decry amnesty must contend with a question they might rather avoid: What do you do about the 11 million illegal immigrants already here?

If you believe the fix is as simple as rounding them up and sending them home, consider the prohibitive personnel and transportation costs — not to mention the visual of police-state sweeps of entire neighborhoods.

There are reasons no one seriously offers this as a solution. In a nation already running massive annual deficits and debt approaching $17 trillion, it makes no fiscal sense.

Neither does leaving these people in the shadows, a half-step removed from American life.

As Sen. Marco Rubio of Florida puts it, “If we do nothing, what we have is de facto amnesty because we don’t know who the undocumented are.” That’s one reason he joined a bipartisan Senate group offering a better way. In addition to the penalties and requirements, the Gang of Eight’s legalization process would not begin until the border was judged secure and other enforcement measures were in place.

Opponents remain stung by memories of the 1986 Simpson-Mazzoli Act, which effectively legalized 3 million illegal immigrants, but never provided the promised enforcement and border security. That truly was amnesty, and it’s no surprise that it led to more, not fewer, illegal crossings over the years.

Opponents would have a point today if the Senate framework or President Barack Obama’s similar plan were as feckless. Instead, their goals are to make legality a stronger inducement than illegality and finally put the amnesty argument in the shadows, where it belongs.