scatterbrained

[1]	hare-brained , rattle-headed , rattle-brained , frivolous , flibbertigibbet , giddy , dazed , flighty , wool-gathering , (Colloq) dippy , dizzy , dopey/dopy , slap-happy

adj.

[1]	rattlebrained , rattlepated , scatty
[2]	flighty , flyaway , head-in-the-clouds