A deliverable is "any unique and verifiable product, result or capability to perform a service that is required to be produced to complete a process, phase, or project." (Quote from the PMBOK glossary.)

During the control quality process the deliverables are compared to the quality requirements, and assuming they meet the requirements, they become verified deliverables. Then in the validate scope process, the verified deliverables are inspected to ensure they meet the required criteria. If they pass, they become accepted deliverables.

Related: scope management, direct and manage project work, define activities, final product, service, or result transition, validation versus verification, product, service, result