The Collaborative International Dictionary of English v.0.48:

Exorbitance \Ex*or"bi*tance\, Exorbitancy \Ex*or"bi*tan*cy\,, n.
   A going out of or beyond the usual or due limit; hence,
   enormity; extravagance; gross deviation from rule, right, or
   propriety; as, the exorbitances of the tongue or of
   deportment; exorbitance of demands. "A curb to your
   exorbitancies." --Dryden.
   [1913 Webster]

         The lamentable exorbitances of their superstitions.
                                                  --Bp. Hall.
   [1913 Webster]

WordNet (r) 3.0 (2006):

exorbitance
    n 1: excessive excess [syn: exorbitance, outrageousness]