write off

Short definition from Wiktionary

Verb

1. 1
   To reduce the book value of (an asset) to zero.
2. 2
   To record (an expenditure) as an expense.
3. 3
   To remove a portion of a debt or an amount of an account owed, counting it as a loss (as a gesture of goodwill for example).
4. 4
   To record a notional expense such as amortization or depreciation.
5. 5
   To treat as a write-off, a total loss, especially something damaged beyond economic repair.
6. 6
   To assign a low value to (somebody or something).
7. 7
   Nonstandard form of write off.

Noun

1. 1
   The cancellation of an item; the amount cancelled or lost.
2. 2
   Something that is now worthless (such as a car after an accident).