Definition & Meaning of "egghead"in English

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

"Egghead" is an American slang term that appeared in the 1920s–1930s, originally used to describe highly educated or intellectual people, drawing on the metaphor of a smooth, egg-shaped head suggesting bookishness or being all brain. It became widely popular during the 1950s, particularly in political contexts, when critics used it to mock experts or academics as impractical, elitist, or out of touch with everyday life. The term is mildly derogatory but can also be used humorously or affectionately; it is rarely neutral but rarely deeply offensive.