What is Invoice?

Legal Definition
An invoice, bill or tab is a commercial document issued by a seller to a buyer, relating to a sale transaction and indicating the products, quantities, and agreed prices for products or services the seller had provided the buyer.

Payment terms are usually stated on the invoice. These may specify that the buyer has a maximum number of days in which to pay and is sometimes offered a discount if paid before the due date. The buyer could have already paid for the products or services listed on the invoice.

In the rental industry, an invoice must include a specific reference to the duration of the time being billed. So in addition to quantity, price, and discount, the invoice amount is also based on duration. Generally, each line of a rental invoice will refer to the actual hours, days, weeks, months, etc., being billed.

From the point of view of a seller, an invoice is a sales invoice. From the point of view of a buyer, an invoice is a purchase invoice. The document indicates the buyer and seller, but the term invoice indicates money is owed or owing.
-- Wikipedia
Legal Definition
Commerce. An account of goods or merchandise sent by merchants to their correspondents at home or abroad, in which the marks of each package, with other particulars, are set forth. Marsh. Ins. 408; Dane's Ab. Index, h. t. An invoice ought to contain a detailed statement, which should indicate the nature, quantity, quality, and price of the things sold, deposited, &c. 1 Pardess. Dr. Com. n. 248. Vide Bill of Lading; and 2 Wash. C. C. R. 113; Id. 155.
-- Bouviers Law Dictionary
Legal Definition
In commercial law. An account of goods or merchandise sent by merchants to their correspondents at home or abroad, in which the marks of each package, with other particulars, are set forth. Marsh. Ins. 408; Dane, Abr. Index. See Merchants' Exch. Co. v. Weisman, 132 Mich. 353, 93 N. W. 870; Southern Exp. Co. v. Hess, 53 Ala. 22; Cramer v. Oppenstein, 16 Colo. 495, 27 Pac. 713. A list or account of goods or merchandise sent or shipped by a merchant to his correspondent, factor, or consignee, containing the particular marks of each description of goods, the value, charges, and other particulars. Jac. Sea Laws, 302. A writing made on behalf of an importer, specifying the merchandise imported, and its true cost or value. And. Rev. Law, ยง 294.
-- Black's Law Dictionary
Legal Definition
A written account of items of goods shipped with their values or prices.
-- Ballentine's Law Dictionary