A plan participant either contributes into a pension plan or is in a position to receive benefit payments from the plan. It includes a retired person receiving distributions from a pension plan, or a beneficiary or dependent named by a contributing member.
Explained further: A plan participant has the right to receive benefit payments from a pension plan, whether it is a defined benefit or a defined contribution pension plan, as long as the requirements under the plan’s contract has been fulfilled. Under most defined benefit pension plans, the member is required to complete a minimum number of years or service in order to qualify for their maximum pension allowable.
Definition courtesy of Investopedia