The Collaborative International Dictionary of English v.0.48:

Extravagant \Ex*trav"a*gant\, a. [F. extravagant, fr. L. extra
   on the outside + vagans, -antis, p. pr. of vagari to wander,
   from vagus wandering, vague. See Vague.]
   1. Wandering beyond one's bounds; roving; hence, foreign.
      [Obs.]
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            The extravagant and erring spirit hies
            To his confine.                       --Shak.
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   2. Exceeding due bounds; wild; excessive; unrestrained; as,
      extravagant acts, wishes, praise, abuse.
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            There appears something nobly wild and extravagant
            in great natural geniuses.            --Addison.
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   3. Profuse in expenditure; prodigal; wasteful; as, an
      extravagant man. "Extravagant expense." --Bancroft.
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The Collaborative International Dictionary of English v.0.48:

Extravagant \Ex*trav"a*gant\, n.
   1. One who is confined to no general rule. --L'Estrange.
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   2. pl. (Eccl. Hist.) Certain constitutions or decretal
      epistles, not at first included with others, but
      subsequently made a part of the canon law.
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WordNet (r) 3.0 (2006):

extravagant
    adj 1: unrestrained, especially with regard to feelings;
           "extravagant praise"; "exuberant compliments";
           "overweening ambition"; "overweening greed" [syn:
           excessive, extravagant, exuberant, overweening]
    2: recklessly wasteful; "prodigal in their expenditures" [syn:
       extravagant, prodigal, profligate, spendthrift]