If you describe someone as an airhead, you are critical of them because you think they are not at all clever and are interested only in unimportant things.
[informal, disapproval]
airhead in British English1
(ˈɛəˌhɛd)
noun
military
an area secured in hostile territory, used as a base for the supply and evacuation of troops and equipment by air
Word origin
C20: modelled on beachhead
airhead in British English2
(ˈɛəˌhɛd)
noun
slang
person lacking intelligence or sense
Word origin
C20
airhead in American English1
(ˈɛrˌhɛd)
noun
an area seized in warfare, esp. by an airborne assault, and held to ensure the continuous bringing in of troops and materiel by air