Source : Webster's Revised Unabridged Dictionary (1913)

Exorbitant \Ex*or"bi*tant\, a. [L. exorbitans, -antis, p. pr. of
   exorbitare to go out of the track; ex out + orbita track: cf.
   F. exorbitant. See {Orbit}.]
   1. Departing from an orbit or usual track; hence, deviating
      from the usual or due course; going beyond the appointed
      rules or established limits of right or propriety;
      excessive; extravagant; enormous; inordinate; as,
      exorbitant appetites and passions; exorbitant charges,
      demands, or claims.

            Foul exorbitant desires.              --Milton.

   2. Not comprehended in a settled rule or method; anomalous.

            The Jews . . . [were] inured with causes exorbitant,
            and such as their laws had not provided for.
                                                  --Hooker.

Source : WordNet®

exorbitant
     adj : greatly exceeding bounds of reason or moderation;
           "exorbitant rent"; "extortionate prices"; "spends an
           outrageous amount on entertainment"; "usorious interest
           rate"; "unconscionable spending" [syn: {extortionate},
           {outrageous}, {steep}, {unconscionable}, {usurious}]