de·pre·ci·a·tion /di-ˌprē-shē-'ā-shən/ n
1: any decrease in the value of property (as machinery) for the purpose of taxation that cannot be offset by current repairs and is carried on company books as a yearly charge amortizing the original cost over the useful life of the property
accelerated depreciation: the depreciation of property that was put into use prior to 1980 which is allowed at a faster rate than normal under the depreciation rules in force before the adoption of the Accelerated Cost Recovery System
straight–line depreciation: depreciation of an asset by a fixed percentage of its original cost based on its estimated life
2: a loss in the value of property due to physical deterioration and wear or to obsolescence and lack of adaptability
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.