Secession is such an ugly word. Let’s call it a constitutional uncoupling.

An amicable divorce would split New York state into three independent districts, each with its own governor and legislature — but would keep it one state for the federal government’s purposes — under a bill introduced by a Buffalo-area lawmaker.

The plan would leave intact New York City’s five boroughs, with their 8.6 million residents, and even keep the name New York.

The city’s immediate suburbs — Nassau, Suffolk, Westchester and Rockland counties would be called “Montauk,” although their 4.2 million citizens would be free to vote for a different name.

And the rest of the Empire State, all 53 upstate counties and their 7.1 million people, would go back to historical basics and become New Amsterdam.

“Rule from Albany does not work in rural America,” Assemblyman David DiPietro (R-East Aurora), the sponsor, told The Post. “One size does not fit all in this state. We’re tired of being second-class citizens.”

The new rules would let each region run its own schools and set its own taxes – and would leave Gov. Cuomo with “about as much power as the queen of England,” said John Bergener Jr. of the Divide NYS Caucus, who helped devise the plan.

“New York City as a whole should be all for it,” said Staten Island supporter Bobby Zahn. “It would free us from Albany’s control over the MTA and schools.”

The exhaustive 24-page bill divvies up New York’s SUNY and CUNY colleges, its court and prison systems, and its roadways.

It abolishes the Board of Regents, eliminates the state attorney general, and sweeps away thousands of state mandates that most counties must pay for with property taxes.

“Eliminate those unfunded mandates and all the upstate counties would be in the black within a year,” Bergener said.

The lighter tax burden would attract industry to upstate counties, DiPietro said, and would save the downstate counties billions in subsidies now paid to its economically needy neighbors.

“We see it as a win-win,” Bergener said.

Similar secession efforts are gaining steam in states like Illinois and California, said Glenn Reynolds, a law professor at the University of Tennessee.

All of them are blue in terms of national politics — but have huge swaths of red districts outside their densely Democratic urban cores.

“The partisan gap between Republicans and Democrats is having an effect,” Reynolds said. “People are self-segregating. Rural areas are redder and urban areas are bluer.”

That makes state governments seem increasingly distant to those in the political minority.

DiPietro’s plan, which would not require federal approval because it would not create a new state, is a first, Reynolds said.

“It’s a clever solution,” he said. “Having three states in one solves a lot of these problems.”