depreciation

noun
1
a decrease in value over a period of time
کاهش ارزش, افت قیمت, افت ارزش, تنزل قیمت
opposite appreciation(4)
2
the act of reducing the value, as stated in the company's accounts, of a particular asset over a particular period of time
استهلاک, کاهش ارزش
the depreciation of fixed assets