Depreciation.

Economic Definition: the decline in the economic value of an asset over time, typically due to physical deterioration, obsolescence, or changes in market conditions.

Accounting Definition: The process of expensing an asset over a specific amount of time, based on a set schedule.

Other Definition: An annual income tax deduction that allows you to recover the cost or other basis of certain property over the time you use the property. It is an allowance for the wear and tear, deterioration, or obsolescence of the property.