Definition & Meaning of "nutcase"in English

What is the origin of the term "nutcase" and how is it used?

"Nutcase" is a slang term that appeared in English in the mid-20th century, combining "nut" (slang for head or, by extension, mind) with "case" to describe a person considered mentally unstable, irrational, or wildly unpredictable. The metaphor links the mind to something fragile or broken, emphasizing unusual or extreme behavior. It is used in informal, often teasing, mocking, or critical contexts, including conversation, media, and casual writing. The term is derogatory and intended to insult or stigmatize; its harshness depends on context and tone.