gratuitous contracta contract where one side is not onerous. Properly speaking, this cannot cover a unilateral promise, for the nature of contract is that it is bilateral. Accordingly, a bilateral gratuitous contract is one where there is merely acceptance of the agreement by one of the parties. In English law it would likely be treated as outside the law of contract because of the need for consideration. In Scotland it is valid and can be proved by any evidence unless subject to REQUIREMENTS OF WRITING.
Collins Dictionary of Law © W.J. Stewart, 2006
GRATUITOUS CONTRACT, civ. law. One, the object of which is for the benefit of the person with whom it is made, without any profit, received or promised, as a consideration for it as, for example, a gift. 1 Bouv. Inst. n. 709.
A Law Dictionary, Adapted to the Constitution and Laws of the United States. By John Bouvier. Published 1856.