Source : Webster's Revised Unabridged Dictionary (1913)

Light-headed \Light"-head`ed\ (-h[e^]d`[e^]d), a.
   1. Disordered in the head; dizzy; delirious. --Walpole.

   2. Thoughtless; heedless; volatile; unsteady; fickle; loose.
      ``Light-headed, weak men.'' --Clarendon. --
      {Light"-head`ed*ness}, n.