Source : Webster's Revised Unabridged Dictionary (1913)

Extravagancy \Ex*trav"a*gan*cy\, n.; pl. {Extravagancies}.
   Extravagance.

Source : WordNet®

extravagancy
     n : the quality of exceeding the appropriate limits of decorum
         or probability or truth; "we were surprised by the
         extravagance of his description" [syn: {extravagance}]