Other forms: airheads
An airhead is a silly, foolish person. If your friend spends fifteen minutes searching for her lost sunglasses, only to find them on top of her head, you can call her an airhead.
While the most popular meaning of airhead is "scatterbrain" or "dingbat," the formal definition of this noun is quite different. Airhead is a military term for a base inside hostile territory where supplies and troops can be kept, and from where soldiers can more safely fly in and out of the area. This 1950s-era meaning comes from the form of the military term beachhead — the slang term is from the 1970s.