What term describes a legal contract that exchanges unequal values between the parties?

The term that describes a legal contract where the exchange involves unequal values between the parties is known as an aleatory contract. In an aleatory contract, the performance of one or both parties is contingent on the occurrence of a specific event, which may result in an unequal exchange of value. This concept is commonly found in insurance agreements, where the premium paid may be significantly lower than the payout received in the event of a loss, reflecting a disparity in value based on uncertainty.

In contrast, other types of contracts mentioned do not emphasize the inequality of value in the same manner. An executable contract refers to a contract that can be enforced, while a unilateral contract involves a promise by one party in exchange for an act by another. A conditional contract is contingent upon the occurrence of a specific event, but it also does not inherently involve the concept of unequal values exchanged. Thus, the unique characteristic of an aleatory contract is what makes it the correct choice for describing a contract with unequal values between parties.