“Two or more military departments working under a single commander to conduct operations in support of a continuing defense or combat mission in a region or an ongoing functional mission; there are currently six unified combatant commands with specific missions in regions throughout the world.”
Blaisure, K. R., Saathoff-Wells, T., Pereira, A., MacDermid Wadsworth, S., & Dombro, A. L. (2015). Serving military families -theories, research, and application. Taylor & Francis Ltd.