Source : Webster's Revised Unabridged Dictionary (1913)

Extravagance \Ex*trav"a*gance\, n. [Cf. F. extravagance. See
   {Extravagant}, and cf. {Extravaganza}.]
   1. A wandering beyond proper limits; an excursion or sally
      from the usual way, course, or limit.

   2. The state of being extravagant, wild, or prodigal beyond
      bounds of propriety or duty; want of moderation; excess;
      especially, undue expenditure of money; vaid and
      superfluous expense; prodigality; as, extravagance of
      anger, love, expression, imagination, demands.

            Some verses of my own, Maximin and Almanzor, cry
            vengeance on me for their extravagance. --Dryden.

            The income of three dukes was enough to supply her
            extravagance.                         --Arbuthnot.

   Syn: Wildness; irregularity; excess; prodigality; profusion;
        waste; lavishness; unreasonableness; recklessness.

Source : WordNet®

extravagance
     n 1: the quality of exceeding the appropriate limits of decorum
          or probability or truth; "we were surprised by the
          extravagance of his description" [syn: {extravagancy}]
     2: the trait of spending extravagantly [syn: {prodigality}, {profligacy}]
     3: excessive spending [syn: {prodigality}, {lavishness}, {highlife},
         {high life}]