What is Bill Of Costs?

Legal Definition
A bill of costs is an itemized list of expenses a prevailing party in a lawsuit or action needs to pay for services procured from a lawyer. It can have varying levels of detail, and should describe the nature of the work done by the lawyer for the client, and any other expenses incurred. Recoverable costs vary by jurisdiction, but often include copying fees, filing fees, travel expenses, court reporter fees, and electronic legal research costs.(example checklist of expenses recoverable in a bill of costs)

In some cases, particularly those in which attorney's fees are part of the relief demanded by the plaintiff, a bill of costs may be submitted to the court, in order to determine how much of the prevailing party's costs the losing party must pay.
-- Wikipedia
Legal Definition
A certified, itemized statement of the amount of costs in an action or suit. Doe v. Thompson, 22 N. H. 219. By the English usage, this term is applied to the statement of the charges and disbursements of an attorney or solicitor incurred in the conduct of his client's business, and which might be taxed upon application, even though not incurred in any suit. Thus, conveyancing costs might be taxed. Wharton.
-- Black's Law Dictionary
Legal Definition
A statement of the items of a party’s costs in an action. See 22 N. H. 217.
-- Ballentine's Law Dictionary