airheaded

from WordNet (r) 3.0 (2006)

airheaded
    adj 1: lacking seriousness; given to frivolity; "a dizzy
           blonde"; "light-headed teenagers"; "silly giggles" [syn:
           {airheaded}, {dizzy}, {empty-headed}, {featherbrained},
           {giddy}, {light-headed}, {lightheaded}, {silly}]

from The Collaborative International Dictionary of English v.0.48

airheaded \airheaded\ adj.
   1. lacking seriousness; given to frivolity; scatterbrained;
      stupid; simple-minded; as, airheaded teenagers. Contrasted
      with {serious}, {solemn}

   Syn: dizzy, empty-headed, featherbrained, giddy, lightheaded,
        light-headed, silly
        [WordNet 1.5]