Source : Webster's Revised Unabridged Dictionary (1913)

Giddiness \Gid"di*ness\, n.
   The quality or state of being giddy.

Source : WordNet®

giddiness
     n 1: an impulsive scatterbrained manner [syn: {silliness}]
     2: a reeling sensation; feeling about to fall [syn: {dizziness},
         {lightheadedness}, {vertigo}]