President Trump angrily denounced the so-called alt-left at a news conference on Tuesday, claiming that the group attacked followers of the so-called alt-right at a white supremacist rally that exploded into deadly violence in Charlottesville, Va., on Saturday.
"What about the 'alt-left' that came charging at the, as you say, the 'alt-right'? Do they have any semblance of guilt?" he asked. There was "blame on both sides," he said. "I have no doubt about it."
Both phrases are part of a broad lexicon of far-right terminology that has become important to understanding American politics during the Trump administration. Many of these terms have their roots in movements that are racist, anti-Semitic and sexist.
Here is a brief guide to the meaning of those expressions and others used by white supremacists and far-right extremists.
The "alt-right" is a racist, far-right movement based on an ideology of white nationalism and anti-Semitism. Many news organizations do not use the term, preferring terms like "white nationalism" and "far right."
The movement's self-professed goal is the creation of a white state and the destruction of "leftism," which it calls "an ideology of death." Richard B. Spencer, a leader in the movement, has described the movement as "identity politics for white people."
It is also anti-immigrant, anti-feminist and opposed to homosexuality and gay and transgender rights. It is highly decentralized but has a wide online presence, where its ideology is spread via racist or sexist memes with a satirical edge.
It believes that higher education is "only appropriate for a cognitive elite" and that most citizens should be educated in trade schools or apprenticeships.
Researchers who study extremist groups in the United States say there is no such thing as the "alt-left." Mark Pitcavage, an analyst at the Anti-Defamation League, said the word had been made up to create a false equivalence between the far right and "anything vaguely left-seeming that they didn't like."
Some centrist liberals have taken to using this term.
"It did not arise organically, and it refers to no actual group or movement or network," Mr. Pitcavage said in an email. "It's just a made-up epithet, similar to certain people calling any news they don't like 'fake news.'"
On Tuesday, Mr. Trump said the "alt-left" was partly to blame for the Charlottesville violence, during which a counterprotester, Heather D. Heyer, was killed.
The "alt-light" comprises members of the far right who once fell under the "alt-right" umbrella but have since split from the group because, by and large, racism and anti-Semitism are not central to its far-right nationalist views, according to Ryan Lenz, the editor of Hatewatch, a publication of the Southern Poverty Law Center. Members of the alt-right mocked these dissidents as "the alt-light."
"The alt-light is the alt-right without the racist overtones, but it is hard to differentiate it sometimes because you're looking at people who sometimes dance between both camps," he said.
The two groups often feud online over "the Jewish Question," or whether Jews profit by secretly manipulating the government and the news media.
"Antifa" is a contraction of the word "anti-fascist." It was coined in Germany in the 1960s and 1970s by a network of groups that spread across Europe to confront right-wing extremists, according to Mr. Pitcavage. A similar movement emerged in the 1980s in the United States and has grown as the "alt-right" has risen to prominence.
For some so-called antifa members, the goal is to physically confront white supremacists. "If they can get at them, to assault them and engage in street fighting," Mr. Pitcavage said. Mr. Lenz, at the Southern Poverty Law Center, called the group "an old left-wing extremist movement."
Members of the "alt-right" broadly portray protesters who oppose them as "antifa," or the "alt-left," and say they bear some responsibility for any violence that ensues — a claim made by Mr. Trump on Tuesday.
But analysts said comparing antifa with neo-Nazi or white supremacist protesters was a false equivalence.
"Cuck" is an insult used by the "alt-right" to attack the masculinity of an opponent, originally other conservatives, whom the movement deemed insufficiently committed to racism and anti-Semitism.
It is short for "cuckold," a word dating back to the Middle Ages that describes a man who knows his wife is sleeping with other men and does not object. Mr. Lenz said the use of the word by the "alt-right" often had racial overtones.
S.J.W. is short for "social justice warrior" and is used by the right as an epithet for someone who advocates liberal causes like feminism, racial justice or gay and transgender rights. It is also sometimes used to imply that a person's online advocacy of a cause is insincere or done for appearances. It became widely used during "GamerGate," a controversy that began in 2014 over sexism in video game subcultures.
Mr. Lenz, whose organization has specific criteria for which groups it classifies as Nazi organizations, said the right used the phrase "to rhetorically address the fact that the left sometimes calls anyone who disagrees with it Nazis." He said the alt-right had created the term so its followers had a similar blanket term to deride the left.
Blood and Soil
Video taken at the white supremacist rally in Charlottesville on Saturday showed marchers chanting "blood and soil." The phrase is a 19th-century German nationalist term that connotes a mystical bond between the blood of an ethnic group and the soil of their country.
It was used as a Nazi slogan in Germany during the 1930s and 1940s and since then "has been transported to neo-Nazi groups and other white supremacists around the world," Mr. Pitcavage said. It is one of several Nazi symbols that have been adopted as a slogan by some members of the "alt-right."
Globalism is sometimes used as a synonym for globalization, the network of economic interconnection that became the dominant international system after the Cold War. The word has become more commonly used since Mr. Trump railed against globalism frequently on the campaign trail.
For the far right, globalism has long had distinct xenophobic, anti-immigrant and anti-Semitic overtones. It refers to a conspiratorial worldview: a cabal that likes open borders, diversity and weak nation states, and that dislikes white people, Christianity and the traditional culture of their own country.
White genocide is a white nationalist belief that white people, as a race, are endangered and face extinction as a result of nonwhite immigration and marriage between the races, a process being manipulated by Jews, according to Mr. Lenz. It is the underlying concept behind far-right, anti-immigration arguments, especially those aimed at immigrants who are not white Christians.
The concept was popularized by Bob Whitaker, a former economics professor and Reagan appointee to the Office of Personnel Management, who wrote a 221-word "mantra" on the subject that ended with the rallying cry: "Anti-racist is code word for anti-white."
Mr. Pitcavage said the concept of white genocide was often communicated online through a white supremacist saying called the Fourteen Words: "We must secure the existence of our people and a future for white children."
The saying was created by David Lane, a white supremacist sentenced to 190 years in prison in connection with the 1984 murder of the Jewish radio host Alan Berg.