Definition & Meaning of "Negative Nancy"in English

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

"Negative Nancy" is a slang expression that appeared in English in the mid-20th century, using the common female name "Nancy" alongside "negative" to label someone persistently pessimistic, critical, or complaining. The term emphasizes habitual gloominess or opposition to optimism. It is used in informal, often teasing, humorous, or mildly critical contexts, such as conversation, media, and casual writing. The term is mildly derogatory and intended to criticize; its harshness depends on tone and context.