wing nut

noun

variants or wingnut

ˈwiŋ-ˌnət 

plural wing nuts or wingnuts

1

usually wing nut : a nut with wings that provide a grip for the thumb and finger

The wing nut on the handle is tightened to secure the blade in the measured position.

—The Home Tool Kit

2

slang : a mentally unsound person

Ever since his mesmerizing performance as a psychotic cop killer in 1979's The Onion Field, Woods has possessed the image of a driven, angry, over-the-edge wing nut.

—Susan Schindehette et al.

3

slang : one who advocates extreme measures or changes (as in politics)

Many on Cheney's staff see Bush's aides as too liberal, while some Bush aides view the vice-presidential staff as wing nuts.

—Nancy Gibbs and Mike Allen

Russia proved highly susceptible to the lure of what, in current parlance, would be called wingnuts (fanatics on the far left or right).

—The Economist

Word History

First Known Use

1834, in the meaning defined at sense 1