Real Dictionary

write down
phrasal verb: When you write something down, you record it on a piece of paper using a pen or pencil.

write down in Accounting
verb: If you write down an asset, you decrease its book value.

write down in American English
to put into written form; write a record of
to set down in writing; record; note

write down in British English
to set down in writing
noun: a reduction made in the book value of an asset

write-down in American English
a reduction in the book value of an asset, as because of depreciation or a decline in market value
noun: a reduction of the entered value of an asset account