wing nut vs wingnut

wing nut

noun
  • One who advocates extreme measures or changes, especially if they hold or are perceived to hold far-right viewpoints; a radical or reactionary. 

  • A nut with wing-like projections to provide leverage in turning with thumb and forefinger. 

  • Someone with large, protruding ears. 

wingnut

noun
  • Someone with crazy or extreme political views (especially extreme conservative views). 

  • Someone perceived as odd, eccentric, and/or extreme. 

  • A member of the air force (in a town that hosts a USAF installation). 

  • A mentally ill homeless person. 

  • A deciduous tree of the genus Pterocarya native to Asia. 

How often have the words wing nut and wingnut occurred in a corpus of books? (source: Google Ngram Viewer )