Amortization

Amortization is the process of reducing a cost or total in regular small amounts [Cambridge Dictionary].
An example of the first meaning is a mortgage on a home, which may be repaid in monthly installments that include interest and a gradual reduction of the principal obligation. Such systematic annual reduction increases the safety factor for the lender by imposing a small annual burden rather than a single, significant, final obligation.
In the second sense, the amortization of an asset, such as a building, a machine, or a mine, over its estimated life reduces its balance-sheet valuation. It charges its cost into the expenses of operation. Such expense is called depreciation or, for exhaustible natural resources, depletion. Some assets, such as property that are abandoned or lost in a catastrophe, may continue to be carried among the firm’s assets until their extinction is achieved by gradual amortization [Encyclopædia Britannica].

Sources:

Amortization. Encyclopædia Britannica. Retrieved from: https://www.britannica.com/topic/amortization

Amortization. Cambridge Dictionary. Retrieved from: https://dictionary.cambridge.org/dictionary/english/amortization