Right-wing nut

"Wingnut" (sometimes wing-nut) is an American political term used as a slur referring to a person who holds extreme, and often irrational, political views.

According to Merriam-Webster, it is "a mentally deranged person" or "one who advocates extreme measures or changes: radical." In American politics, the term is more often aimed at members of the political right than those of the political left, for which the alternative term "moonbat" is more often used. David M. Herszenhorn of The New York Times has defined a "wing nut" as "a loud darling of cable television and talk radio whose remarks are outrageous but often serious enough not to be dismissed entirely." In his book Wingnuts: How the Lunatic Fringe is Hijacking America author and columnist John Avlon defined a wingnut as, "someone on the far-right wing or far-left wing of the political spectrum—the professional partisans, the unhinged activists and the paranoid conspiracy theorists. They're the people who always try to divide rather than unite us".

Responding to its use in an essay by Peter Coyote, Sean Parnell of the Center for Competitive Politics wrote:

Moreover, you're [sic] use of the term "wing-nut minorities" is interesting for one who decries the incivility of political discourse today. I haven't read the new and updated Miss Manners for Politics yet, but I'm guessing I'm not going to find a section in there approving of the use of pejorative namecalling and broadly delegitimizing and demonizing your opponents.

Coyote responded with a sarcastic retort:

Okay. I've been rightly taken to task by Sean Parnell for my rudeness in calling people with whom I disagree "wing-nuts." He's right and I'm wrong. But, what would you call people that believe that fully automatic weapons and cop-killer bullets should be freely available; who bomb abortion clinics and advocate the murder of doctors who perform abortions; who believe that anyone who is not a Christian is doomed to Hell, and people who would elevate Creationism to the status of science? Give me a polite name and I'll use it.

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Wikipedia