Which term defines a promise exchange in a one-sided agreement in contract law?

In contract law, a unilateral contract is defined as a promise exchange where one party makes a promise that is open for acceptance by the performance of a specific act by another party. This means that only one party is obligated to fulfill their promise once the other party performs the act as stipulated in the contract.

For example, if someone offers a reward for the return of a lost pet, the offeror is making a unilateral contract. The person who finds and returns the pet is not obligated to do so, but if they do, the offeror is bound to pay the reward. This type of agreement is distinct because the promise of the offeror is dependent solely on the action taken by the other party; the offeree does not have to make any promises in return.

In contrast, a bilateral contract involves mutual promises between two parties, where each party is both a promisor and a promisee. Implied contracts arise from the actions or conduct of the parties rather than explicit agreements. Oral contracts are spoken agreements that can be either bilateral or unilateral but do not inherently define the one-sided promise characteristic that unilateral contracts hold.