What is Counterpart?

Legal Definition
Contracts. Formerly each party to an indenture executed a separate deed; that part which was executed by the grantor was called the original, and the rest the counterparts. It is now usual for all the parties to execute every part, and this makes them all originals. 2 Bl. Com. 296.

2. In granting lots subject to a ground rent reserved to the grantor, both parties execute the deeds, of which there are two copies; although both are original, one of them is sometimes called the counterpart. Vide 12 Vin. Ab. 104; Dane's Ab. Index, h. t.; 7 Com. Dig. 443; Merl. Repert. mots Double Ecrit.
-- Bouviers Law Dictionary
Legal Definition
In conveyancing. The corresponding part of an instrument; a duplicate or copy. Where an instrument of conveyance, as a lease, is executed in parts, that is, by having several copies or duplicates made and interchangeably executed, that which is executed by the grantor is usually called the "original," and the rest are "counterparts;" although, where all the parties execute every part, this renders them all originals. 2 Bl. Comm. 296; Shep. Touch. 50. Roosevelt v. Smith, 17 Misc. Rep. 323, 40 N. Y. Supp. 381. See Duplicate See Counterpart writ.
-- Black's Law Dictionary
Legal Definition
A duplicate; one of the parts of an indenture. See 17 Misc. Rep. 323, 40 N. Y. Supp. 381.
-- Ballentine's Law Dictionary