e·vac·u·ate / iˈvakyəˌwāt/ • v. [tr.] 1. remove (someone) from a place of danger to a safe place: several families were evacuated from their homes. ∎  leave or cause the occupants to leave (a place of danger): fire alarms forced staff to evacuate the building.2. technical remove air, water, or other contents from (a container): when it springs a leak, evacuate the pond. ∎  empty (the bowels or another bodily organ). ∎  discharge (feces or other matter) from the body.

evacuate XV. f. pp. stem of L. ēvacuāre, f. E- + vacuus empty; see -ATE3.
So evacuation XIV. — late L. Hence evacuee XX.