Definitions of separation:

• noun:   the act of dividing or disconnecting
• noun:   the social act of separating or parting company

  Example: "The separation of church and state"

• noun:   sorting one thing from others

  Example: "The separation of wheat from chaff"

• noun:   termination of employment (by resignation or dismissal)
• noun:   coming apart
• noun:   the space where a division or parting occurs

  Example: "He hid in the separation between walls"

• noun:   the state of lacking unity
• noun:   (law) the cessation of cohabitation of man and wife (either by mutual agreement or under a court order)
• noun:   the distance between things

  Example: "Fragile items require separation and cushioning"