natural wastage
noun [ U ] business UK uk/ˌnætʃ.ər.əl ˈweɪ.stɪdʒ/ us/ˌnætʃ.ɚ.əl ˈweɪ.stɪdʒ/ (also wastage); (US attrition)
（由离职引起的）自然减员
a reduction in the number of people who work for an organization that is achieved by not replacing those people who leave