Source : Webster's Revised Unabridged Dictionary (1913)

Amortise \A*mor"tise\, v., Amortisation \A*mor`ti*sa"tion\, n.,
Amortisable \A*mor"tis*a*ble\, a., Amortisement
\A*mor"tise*ment\, n.
   Same as {Amortize}, {Amortization}, etc.

Source : WordNet®

amortisation
     n 1: the reduction of the value of an asset by prorating its cost
          over a period of years [syn: {amortization}]
     2: payment of an obligation in a series of installments or
        transfers [syn: {amortization}]