gratuitous gift. A gift made without consideration, as most gifts are. Strictly speaking, the term looks redundant, but it answers to the donum gratuitum of Roman law.

https://books.google.pl/books?id=sgNfDwAAQBAJ&pg=PA758&lpg=P...

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Note added at 57 mins (2019-06-13 14:04:46 GMT)
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A bonus may also be defined as a gratuitous gift given to an employee in addition to his regular salary in appreciation of services efficiently rendered.
https://attorneygeneral.nd.gov/sites/ag/files/Legal-Opinions...

In May 2001, the plaintiff and the defendant executed a co- ownership agreement, which when read by the court, was evidence of an intention by the plaintiff to transfer the property as a gratuitous gift to the defendant.
http://disinherited.com/rebutting-presumption-resulting-trus...

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Note added at 1 hr (2019-06-13 14:16:14 GMT)
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Moreover, defendant also contends that at no time was plaintiff promised any sort of compensation for her idea and plaintiff did not submit her suggestion to defendant in any form other than as a gratuitous gift, without any expectation of compensation.
https://www.leagle.com/decision/1986874130misc2d7441728

Past consideration is not consideration, and consideration must move from the promisee (“offeree”) to the promisor (“offeror”). If a promise is unsupported by consideration it is regarded as a gratuitous gift which will not be enforced in contract law unless contained in a deed under seal.
http://comasters.com.au/?portfolio_page=contract-law

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Note added at 1 hr (2019-06-13 14:36:12 GMT)
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Gift

A voluntary transfer of property or of a property interest from one individual to another, made gratuitously to the recipient. The individual who makes the gift is known as the donor, and the individual to whom the gift is made is called the donee.

If a gratuitous transfer of property is to be effective at some future date, it constitutes a mere promise to make a gift that is unenforceable due to lack of consideration. A present gift of a future interest is, however, valid.
https://legal-dictionary.thefreedictionary.com/gift