Airhead (slang)
Airhead is a popular term for a foolish, slow witted or shallow person that has been current since the '60's, though the term became more popular in the 80's.
Airhead literally means that a persons head is filled with nothing but air (ie. that they lack a brain).
Technically an airhead may be either male or female but generally the term refers to a young woman of (seemingly) limited intelligence, shallow or ditsy personality and obsessive about her looks. In this use of the term an airhead can be considered a stereotype analogous to a bimbo or a Dumb blonde.
Less commonly airhead can also refer to a (male) Stoner.