ex·or·bi·tant 
(ĭg-zôrbĭ-tənt)
(ĭg-zôrbĭ-tənt)adj.
Going beyond what is reasonable or customary, especially in cost or price: exorbitant rent; exorbitant telephone bills.
[Middle English, aberrant, flagrant, from Old French, excessive, extreme, from Late Latin exorbitāns, exorbitant-, present participle of exorbitāre, to deviate : Latin ex-, ex- + Latin orbita, path, track; see ORBIT.]
ex·orbi·tant·ly adv.