Definitions of occupation:

• noun:   the act of occupying or taking possession of a building

  Example: "Occupation of a building without a certificate of occupancy is illegal"

• noun:   the principal activity in your life that you do to earn money
• noun:   any activity that occupies a person's attention

  Example: "He missed the bell in his occupation with the computer game"

• noun:   the control of a country by military forces of a foreign power
• noun:   the period of time during which a place or position or nation is occupied

  Example: "During the German occupation of Paris"