From WordNet (r) 2.0 (August 2003) [wn]:
empty-headed
adj : lacking seriousness; given to frivolity; "a dizzy blonde";
"light-headed teenagers"; "silly giggles" [syn:
airheaded, dizzy, featherbrained, giddy,
light-headed, lightheaded, silly]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
empty-headed \empty-headed\ adj.
lacking seriousness; given to frivolity.
Syn: airheaded, dizzy, featherbrained, giddy, lightheaded,
light-headed, silly.
[WordNet 1.5]