Wiktionary
vb. 1 (context accounting English) To reduce an asset's book value to zero 2 (context accounting English) To record an expenditure as an expense. 3 (context accounting English) To remove a portion of a debt or an amount of an account owed to you counting it as a loss (as a gesture of goodwill for example) 4 (context accounting English) To record a notional expense such as amortization or depreciation. 5 Figuratively, to assign a low value to something.
WordNet
v. concede the loss or worthlessness of something or somebody; "write it off as a loss"
write something fluently, and without hesitation
cancel (a debt)
reduce the estimated value of something; "For tax purposes you can write off the laser printer" [syn: write down]