airheaded
/ˈɛrhɛdəd/
adjective
(of a person) silly or foolish.
stupid,unintelligent,idiotic,foolish,silly,brainless,half-witted,witless,vacuous,vapid,hare-brained,feather-brained,birdbrained,pea-brained,scatterbrained,giddy,skittish,flighty,frivolous,thoughtless