What legal term describes a contract that becomes enforceable only upon a certain event happening?

The term that describes a contract which is enforceable only upon the occurrence of a certain event is known as a conditional contract. This type of contract includes specific provisions that trigger the obligations of the parties involved only if particular conditions are met. For example, a conditional contract may stipulate that one party's duty to perform is contingent upon a third party’s approval or a specific date being reached.

In a conditional contract, the enforceability hinges entirely on the predefined event occurring. If the event does not happen, then the contract remains unenforceable. This characteristic is what distinguishes conditional contracts from other types, such as void contracts, which are never enforceable, or executed contracts, which have been fully performed by all parties. Implied contracts, on the other hand, arise from actions or circumstances rather than explicit terms, and therefore do not fit the description of requiring a specific event for enforcement.