The period of service, expressed in a yearly figure, for which a worker has established pension credits for a pension plan. Pension benefits are typically based on the worker’s pensionable service and highest average salary.
Explained further: The pensionable service value calculated for each worker is most commonly based on the employer’s record of the actual units (hours, years etc) worked. This includes any periods of purchased service which the pensioner has opted to purchase. Pension plans may have differing calculations for pensionable service, so it is important for prospective pensioners to be aware of the terms of their pension plan.
Definition courtesy of Investopedia