Definitions of agency:

• noun:   a business that serves other businesses
• noun:   an administrative unit of government

  Example: "The Central Intelligence Agency"

• noun:   the state of being in action or exerting power

  Example: "The agency of providence"

• noun:   how a result is obtained or an end is achieved

  Example: "An example is the best agency of instruction"

• noun:   the state of serving as an official and authorized delegate or agent