Source : Webster's Revised Unabridged Dictionary (1913)

Fatuity \Fa*tu"i*ty\, n. [L. fatuitas, fr. fatuus foolish: cf.
   F. fatuit['e] Cf. {Fatuous}.]
   Weakness or imbecility of mind; stupidity.

         Those many forms of popular fatuity.     --I Taylor.

Source : WordNet®

fatuity
     n : a ludicrous folly; "the crowd laughed at the absurdity of
         the clown's behavior" [syn: {absurdity}, {fatuousness}, {silliness}]