Amortization is an accounting term that means the depreciation, depletion, or charge-off to expense of intangible and tangible assets over a period of time.
It is the running down or payment of a loan by installments. An example is a repayment mortgage on a house, which is amortized by making monthly payments that over a pre-agreed period of time cover the value of the loan plus interest. With loans that are not amortized, the borrower pays only interest during the period of the loan and then repays the sum borrowed in full.
For example, in the energy industry the term often means either (1) the periodic charge-off to expense of the costs associated with nonproducing mineral properties incurred prior to the time when they are developed and entered into production or (2) the systematic charge-off to expense of those costs of productive mineral properties (including tangible and intangible costs of prospecting, acquisition, exploration, and development) that had been initially capitalized (or deferred) prior to the time the properties entered into production, and thereafter are charged off as minerals are produced.