Which type of contract is often referred to as a contingent contract?

A contingent contract, which is often aligned with the concept of an aleatory contract, involves an agreement where the performance of at least one party depends on the occurrence of a specific event that is uncertain. The defining feature of an aleatory contract is that it is based on uncertain events, meaning the obligations of the parties are contingent upon the occurrence of a certain event. For example, insurance contracts are a common type of aleatory contract; the insurer's obligation to pay claims is dependent on the occurrence of an insured event, such as an accident or theft.

In contrast, bilateral contracts involve mutual promises where both parties commit to fulfilling their respective obligations. Quasi contracts are not actual contracts but are imposed by law to prevent unjust enrichment. Express contracts are formed explicitly through clear written or spoken terms, without the uncertainty aspect that characterizes contingent contracts.

Thus, the designation of a contingent contract as an aleatory contract is due to the fundamental reliance on uncertain events that influence the contractual obligations of the parties involved.