evacuation

noun

1. The act of evacuating; leaving a place in an orderly fashion, especially for safety.
2. Withdrawal of troops or civils from a town, fortress, etc.
3. The act of emptying, clearing of the contents, or discharging, including creating a vacuum.
4. Voidance of any matter by the natural passages of the body or by an artificial opening; defecation; also, a diminution of the fluids of an animal body by cathartics, venesection, or other means.