empty-headed

from WordNet (r) 3.0 (2006)

empty-headed
    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

empty-headed \empty-headed\ adj.
   lacking seriousness; given to frivolity.

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

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