What does "wingnut" mean?

A deciduous tree of the genus Pterocarya native to Asia.

What is a synonym for "wingnut"?

Common synonyms include: crank, fanatic, fastener, nut, wingnuts, zealot.

/ˈwɪŋˌnʌt/ noun, slang

noun, slang ·Moderate ·College level

Noun

1
A deciduous tree of the genus Pterocarya native to Asia.
2
A person who is or seems odd, eccentric, or crazy; especially, someone with bizarre or extreme political views. derogatory, informal
"Near-synonyms: nut, nut job, nut case, crank, weirdo; see also Thesaurus:strange person, Thesaurus:mad person"
3
A member of the air force (in a town that hosts a USAF installation). slang
4
A person with large ears. informal, slang
5
Alternative form of wing nut (“(mechanical) nut with wing-like projections”). alt-of, alternative

"Near-synonyms: nut, nut job, nut case, crank, weirdo; see also Thesaurus:strange person, Thesaurus:mad person"

From wing + nut. The political sense is a shortening of "right-wing nut".