It stands for net book value; the value at which an entity reports an asset on its balance sheet (statement of financial position). It is calculated as the original cost (acquisition cost) of an asset less accumulated depreciation, accumulated amortization, accumulated depletion or accumulated impairment, as applicable.

More specifically, net book value is equal to the original cost (book value) less accounting depreciation and other types of value write-down measures. net book value does not take into consideration specific factors that would usually be considered in a proper market valuation.

It is also known as depreciated cost or net asset value.