1. : service (as of troops, company agents, social-service workers) in the field
2. : labor in the fields performed by Negro slaves in America before 1865
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field service,
service, especially by civil servants and social workers, performed away from the main office or center: ยป
All the executive departments have headquarters in Washington, but about 90 of every 100 employees work elsewhere in field services (William G. Carleton).
Useful english dictionary. 2012.