wing nut

His views might be extreme, but he did not come off as a wingnut while presenting them.
Barry Goldwater, Father of the Tea Party|Nicolaus Mills|July 16, 2014|DAILY BEAST
Rep. Steve Stockman (R-TX) is a grifter and a wingnut, but is he possibly a felon too?
Ethics Office Sees Evidence Republican Congressman Broke the Law|Ben Jacobs|June 11, 2014|DAILY BEAST
He's still out there trying to pump up the Tea Party wingnut vote.
Virginia Is for Sanity Lovers|Michael Tomasky|November 4, 2013|DAILY BEAST
This idea is really the spawn of Mark Levin, the wingnut radio host, who has (of course) written a book about it.
Mark Levin's Nutty Constitutional Convention Idea|Michael Tomasky|August 29, 2013|DAILY BEAST

Well, we learned something new about what's going on in wingnut land.
The Obama Press Conference|Michael Tomasky|April 30, 2013|DAILY BEAST
It has no latch and the throttle lever is held in any desired setting by the wingnut and quadrant shown in figure 18.
The 'Pioneer': Light Passenger Locomotive of 1851|John H. White

British Dictionary definitions for wing nut

wing nut

noun

a threaded nut tightened by hand by means of two flat lugs or wings projecting from the central bodyAlso called: butterfly nut

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012