Before revision: In accounting, amortization refers to expensing the acquisition cost minus the residual value of intangible assets in a systematic manner over their estimated "useful economic lives" so as to reflect their consumption, expiry, and obsolescence, or other decline in value as a result of use or the passage of time.
After revision: In accounting, amortization is a method of obtaining the expenses incurred by an intangible asset arising from a decline in value as a result of use or the passage of time.