Definition & Meaning of "butterhead"in English

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

"Butterhead" is an English slang insult that appeared in the 19th–20th centuries, combining "butter" (suggesting softness or lack of substance) with "head" to imply someone has a soft, empty, or ineffective mind. The term likens a person's intellect to something easily squished or insubstantial. It has been used in informal speech, schoolyard teasing, and literary contexts to describe foolish or stupid people. The term is clearly derogatory but mild, rarely considered highly offensive, and is usually employed to mock rather than attack seriously.