What is Bargain?

Legal Definition
A mutual undertaking, contract or agreement. A contract or agreement between two parties, the one to sell goods or lands, and the other to buy them. Hunt v. Adams, 5 Mass. 360, 4 Am. Dec. 68 ; Sage v. Wilcox, 6 Conn. 91; Bank v. Archer, 16 Miss. 192. "If the word 'agreement' imports a mutual act of two parties, surely the word 'bargain' is not less significative of the consent of two. In a popular sense, the former word is frequently used as declaring the engagement of one only. A man may agree to pay money or to perform some other act, and the word is then used synonymously with 'promise' or 'engage.' But the word 'bargain' is seldom used, unless to express a mutual contract or undertaking." Packard v. Richardson. 17 Mass. 131, 9 Am. Dec. 123.
See also
-- Black's Law Dictionary
Legal Definition
A contract or agreement to buy on one side and sell on the other. See 5 Mass. 358, 4 Am. Dec. 68.
-- Ballentine's Law Dictionary