As July 4 and its barbecues arrived this year, the activist and former N.F.L. quarterback Colin Kaepernick declared, “We reject your celebration of white supremacy.”

The movie star Mark Ruffalo said in February that Hollywood had been swimming for a century in “a homogeneous culture of white supremacy.”

The director of the Metropolitan Museum of Art, one of New York City’s most prestigious museums, acknowledged this summer that his institution was grounded in white supremacy, while four blocks uptown, the curatorial staff of the Guggenheim decried a work culture suffused in it.

The Los Angeles Times editorial board issued an apology two weeks ago describing itself as “deeply rooted in white supremacy” for at least its first 80 years. In England, the British National Library’s Decolonising Working Group cautioned employees that a belief in “color blindness” or the view that “mankind is one human family” are examples of “covert white supremacy.”

In a time of plague and protest, two words — “white supremacy” — have poured into the rhetorical bloodstream with force and power. With President Trump’s overt use of racist rhetoric, a spate of police killings of Black people, and the rise of far-right extremist groups, many see the phrase as a more accurate way to describe today’s racial realities, with older descriptions like “bigotry” or “prejudice” considered too tame for such a raw moment.

News aggregators show a vast increase in the use of the term “white supremacy” (or “white supremacist”) compared with 10 years ago. The New York Times itself used the term fewer than 75 times in 2010, but nearly 700 times since the first of this year alone. Type the term into Twitter’s search engine and it pops up six, eight or 10 times each minute.

The meaning of the words has expanded, too. Ten years ago, white supremacy frequently described the likes of the Ku Klux Klan and David Duke, the neo-Nazi politician from Louisiana. Now it cuts a swath through the culture, describing an array of subjects: the mortgage lending policies of banks; a university’s reliance on SAT scores as a factor for admissions decisions; programs that teach poor people better nutrition; and a police department’s enforcement policies.

Yet the phrase is deeply contentious. Influential writers such as Ta-Nehisi Coates and Ibram X. Kendi, a Boston University professor, have embraced it, seeing in white supremacy an explanatory power that cuts through layers of euphemism to the core of American history and culture. It speaks to the reality, they say, of a nation built on slavery. To examine many aspects of American life once broadly seen as race neutral — such as mortgage lending or college faculty hiring — is to find a bedrock of white supremacy.

“It is not hyperbole to say that white supremacy is resting at the heart of American politics,” Keeanga-Yamahtta Taylor of Princeton, a socialist activist and professor of African-American studies, said in a speech in 2017.

But some Black scholars, businessmen and activists — on the right and the left — balk at the phrase. They hear in those words a sledgehammer that shocks and accuses, rather than explains. When so much is described as white supremacy, when the Ku Klux Klan and a museum art collection take the same descriptor, they say, the power of the phrase is lost.

Prof. Orlando Patterson, a sociologist at Harvard University who has written magisterial works on the nature of slavery and freedom, including about his native Jamaica, said it was too reminiscent of the phrases used to describe apartheid and Nazi Germany.

“It comes from anger and hopelessness and alienates rather than converts,” he said.

The label also discourages white and Black people from finding commonalities of experience that could move society forward, Professor Patterson and others said.

“It racializes a lot of problems that a lot of people face, even when race is not the answer,” Professor Patterson said.

Glenn C. Loury, a conservative-leaning economics professor at Brown University, hears in the term an attempt to spin a mythic narrative about a fallen America.

“So we declare structures of our country are implacably racist,” Professor Loury said. “On the other hand, we make appeals to have a conversation with that country which is mired in white supremacy? The logic escapes me.”

Then there are those whose cultural signposts are found outside the Black-white divide. The essayist Wesley Yang, the son of Korean immigrants and the author of “The Souls of Yellow Folk,” often examines racial identity and has found himself watching the debate over these words as if through a side window. Did this thing called white supremacy really so neatly define the lives of Black people and Latinos and Asians?

“The phrase is destructive of discourse,” he said. “Once you define it as something that has a ghostly essence, it’s nowhere and everywhere.”

A new term for a familiar problem

The rise in the use of “white supremacy” is in some ways a puzzle easily solved. Prof. John McWhorter of Columbia University, a linguist, explained that such expressions are like a crocodile’s teeth. Old ones wear down and are shed; new and sharper ones appear.

“Words lose their rhetorical strength,” he said. “Fifty years ago, in a Norman Lear sitcom like Archie Bunker, if someone was accused of being ‘prejudiced,’ you sucked in your breath.”

As legally sanctioned segregation ended in the 1960s, intellectuals and activists sought to describe a world in which laws had changed and yet much remained ineffably the same. The words “prejudice,” “bias” and “intolerance” came to be seen as insufficient. The Rev. Dr. Martin Luther King Jr., Malcolm X and James Baldwin wrote of white supremacy as part of their searching critiques of American society.

The phrase traveled into popular culture along several lines of transmission. In academia in the early 1980s, Richard Delgado, a University of Alabama law school professor, and Prof. Derrick Bell of Harvard Law School developed what became known as critical race theory. Favoring storytelling and the righting of wrongs, it held that white supremacy and racism were longstanding fixtures of American history and life, and that individual racism was less remarkable than the systemic racism embedded in the culture, including the law.

Professor Delgado told me he saw in “white supremacy” an effective descriptive tool. “It remains useful for coming to grips with whiteness, with old boys’ networks, with the role of color and who gets ahead or who gets to live in one neighborhood or another,” he said.

Critical race theory, however, met with decades of resistance, from conservatives and from liberals alike, who saw its claims as too sweeping.

But in 2008, the concept broke through to a broad audience, when Mr. Coates started writing a series of essays in The Atlantic and several popular books, in which he argued that the United States was mired from its inception in the muck of white supremacy and racist violence. Schools, language, the economy and politics: Nearly everything in the United States, he wrote, bore the mark of a white supremacist identity.

“Black nationalists have always perceived something unmentionable about America that integrationists dare not acknowledge — that white supremacy is not merely the work of hotheaded demagogues, or a matter of false consciousness, but a force so fundamental to America that it is difficult to imagine the country without it,” Mr. Coates wrote in a seminal essay in The Atlantic in 2014.

Mr. Coates’s work helped reshape how scholars and activists talked about racism. A new directness took hold. “‘Structural racism’ is more direct in its condemnation,” noted Khiara Bridges, a law professor at the University of California, Berkeley, School of Law. “But it still obscured who was winning.”

She added, “There is nothing implicit about ‘white supremacy.’ It’s whites who are winning, and people of color who are losing.”

A slogan, or a social reality?

Angela D. Dillard is a professor of Afro-American and African studies at the University of Michigan. She has examined the history of racism in her work and views it as a near-permanent feature of American society.

Yet the words “white supremacy” catch in her throat.

“It’s really jarring to the modern ear; it gets in the way,” she says. “It conjures the movie ‘Birth of a Nation’ and Richard Wagner booming over the speakers.”

It became more jarring when she heard the words applied to herself. She was an associate dean of students at Michigan when the university decided that it could not, as a public institution, deny Richard Spencer, a white racist and neo-Nazi, a chance to speak on campus.

Student protesters staged a sit-in at the dean’s office in 2017 and held up signs stating: “U of M Upholds White Supremacy as Usual.”

“To have students screaming at me that I was supposed to dismantle a white supremacist university,” said Professor Dillard, who is Black. “What does that even mean? It was like they were reading me out of the race.”

Barbara J. Fields, a professor of history at Columbia University who describes herself as Afro-American, said the phrase was a slogan rather than a belief. In the book “Racecraft,” which explores the relationship between racism and inequality, she quoted approvingly her old mentor, C. Vann Woodward, the historian of the American South, who argued that holding power over Black people allowed the white upper class to dominate lower-class white people as well, by using racism to divide them.

“The real question,” Mr. Woodward wrote, “was which whites should be supreme.”

“I wish people would stop talking about white supremacy and privilege,” Professor Fields said in an interview. In an allusion to the Sermon on the Mount and class powerlessness, she added, “If you believe that white working people are privileged and responsible for all your pain, tell me when the meek inherited the earth.”

Still others see in the phrase a sometimes precise definition of American realities. Denise Scott spent decades working in nonprofit housing and recently ascended to the heart of the establishment, the board of the Federal Reserve Bank of New York.

Not long after her appointment, Ms. Scott asked to review the Fed data on home sales since the 2008 recession. The housing market had rebounded for everyone save Black Americans. Too many banks, Ms. Scott said, had pushed risky high-rate mortgages on Black families, draining them of wealth needed to pay college tuitions and retirements.

“They targeted Black communities and dumped debt and said, ‘Look at those stupid people who took on costs they could not afford,’” she said.

That, Ms. Scott said, was not just bad or corrupt policy. It was white supremacy at work.

“We used to draw a bold line between those who went around hanging blacks and other behavior,” she said. “We’ve come to realize white supremacy permeates our society.”

‘I don’t see white supremacy’

John W. Rogers Jr. is the founder, chairman and chief executive of Ariel Investments, one of the larger Black-owned investment firms in the nation, with many billions of dollars under management. (He also sits on the board of The New York Times.)

Asked about white supremacy, he speaks of his great-grandfather J.B. Stradford, who was born to a freed slave, graduated from Oberlin College and, in the first decades of the 20th century, became a leading citizen in Tulsa, Okla., in the Greenwood neighborhood known as Black Wall Street.

He opened the Stradford Hotel, the largest Black-owned hotel in America at the time, with posh suites, dining rooms, a saloon and a pool hall, and planned to build more to serve a rising Black bourgeoise.

Then World War I ended, and a wave of falling wages, anxiety and racism among the white citizens of Tulsa led to a riot in 1921. White residents destroyed Black Wall Street, leaving more than 200 Black Americans dead and 35 blocks gutted.

Mr. Stradford was investigated for the act of defending himself and his neighborhood. He fled to Chicago, where his son — Mr. Rogers’s grandfather — defended him against extradition attempts.

The tale did not end there. Mr. Rogers’s mother, Jewel, became the first Black woman to graduate from the University of Chicago Law School. None of the city’s premier law firms would hire her. “She was still working at age 75, while mediocre white lawyers had retirement homes in West Palm Beach,” Mr. Rogers recalled.

His father was a Tuskegee airman in World War II and a county judge. He purchased homes but as a Black man,he could buy only on Chicago’s South Side, and the properties appreciated slowly.

“They didn’t really have a chance to create any true wealth,” Mr. Rogers said of his parents.

Mr. Rogers sees unquestionable truths: He has been terrifically successful, and racism deprived his family of millions of dollars in generational wealth.

Asked if white supremacy defined his family’s story, Mr. Rogers paused and replied: No. White supremacy, he said, was what his great-grandfather endured in Tulsa and Representative John Lewis faced in Selma. To argue that such primal violence and discrimination extended to the modern day struck him as defeatist.

But he listens to some chief executives insist they have vanquished bias and feels a swell of impatience.

“You see your grandparents not treated fairly, and your parents, and your resentment builds,” Mr. Rogers, 62, said.

“I don’t see white supremacy,” he said. “But many well-meaning whites don’t understand the challenges.”

Kitty Bennett contributed research.