Definitions of Empire:

• noun:   an eating apple that somewhat resembles a McIntosh; used as both an eating and a cooking apple
• noun:   a group of countries under a single authority

  Example: "The British empire"

• noun:   a monarchy with an emperor as head of state
• noun:   the domain ruled by an emperor or empress
• noun:   a group of diverse companies under common ownership and run as a single organization