Airhead
-She's really very nice, but she is a bit of an airhead.
-If you don't want people to think you are an airhead, you have to keep up with what is in the world.
-The children of my rich parents become airheads.
Meaning: A stupid person.
Origin: You've got air in your head , where brains are supposed to be. Dates back to between 1975 and 1980.
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Other examples:
1. To those airheads who believe plastic surgeries can bring them beauty, I want to tell them to stay fit and natural is the key to beauty.
2. Sometimes when people first meet Cathy, they think she is a bit of a pretty airhead.
3. Amanda ends up being much less of an airhead than she initially appears.