Contra Assets ?

Accumulated Depriciation is a contra asset

Anything which reduces the value of an asset is called contra asset like accumulated depreciatio.

A Contra Asset is a negative asset account that is designed to offset the balance in the asset account with which it is paired. The purpose of a contra asset account is to store a reserve that reduces the balance in the paired account. The natural balance in a contra asset account is a credit balance, as opposed to the natural debit balance in all other asset accounts. 

Contra assets may be stated in separate line items on the balance sheet. Or, if they contain relatively minor balances, they may be aggregated with their paired accounts and presented as a single line item in the balance sheet.

For example: The accumulated depreciation account is a contra asset account, and it is paired with the fixed assets account. When combined, the two accounts show the net book value of a company's fixed assets.