Hillary Clinton delivered a defiant rebuke to President Trump yesterday — without once mentioning him by name — slamming his proposed budget as a “con,” dissing the size of his inauguration crowd and even likening him to Richard Nixon.

Returning to her alma mater, Wellesley College, Clinton used one of her few public speeches since losing last year’s election to whack the White House, earning rounds of cheers, applause and laughter from the ultra-liberal campus.

“When people in power invent their own facts and attack those who question them, it can mark the beginning of the end of a free society,” the former Democratic presidential nominee warned graduates on the 48th anniversary of her own student commencement speech.

“You are graduating at a time when there is a full-fledged assault on truth and reason,” Clinton said.

Clinton targeted Trump repeatedly, mostly indirectly. Recalling her own graduation in 1969, she described President Nixon’s fall from grace in terms that mirrored Trump’s controversies, from the ongoing FBI investigation into his campaign’s Russia ties to his recent firing of FBI Director James Comey.

“We were furious about the past presidential election,” Clinton said, “of a man whose presidency would eventually end in disgrace with impeachment for obstruction of justice … after firing the person running the investigation into him at the Department of Justice.”

The line drew waves of cheers, even though Nixon had not been impeached before he resigned. Clinton worked as a young staffer on the House Judiciary Committee that investigated his actions during Watergate and drew up articles of impeachment against him.

Clinton also took jabs directly at the White House budget, knocking it for its “unimaginable cruelty on the most vulnerable among us.”

“And to top it off, it is shrouded in a trillion-dollar mathematical lie,” she said. “Let’s call it what it is. It’s a con. They don’t even try to hide it.”

Clinton, who jokingly said she got over her election loss with the help of Chardonnay, denounced the social media trolling that helped fueled controversies on the campaign trail, including the so-called “PizzaGate” conspiracy theory “about child abuse rings operating out of pizza parlors.”

“Some are even denying things we see with our own eyes. Like the size of crowds,” she said to laughter, an outright jab to Trump’s inauguration claims. “And then defending themselves by talking about ‘alternative facts.’ ”

Clinton also plugged her newly created political group, Onward Together, as a vehicle to “help recruit and train future leaders.” She pointed to it as evidence that she doesn’t plan to fade away, and repeated a line she made during her commencement address as a student nearly a half-century ago.

“The challenge now is to practice politics as the art of making what appears to be impossible, possible,” she said. “That was true then. It’s truer today.”