'evacuation' originates from Latin, specifically the verb 'evacuare', where 'e-' (or 'ex-') meant 'out' and 'vacare' meant 'to be empty'.

'evacuare' passed into Late Latin and Old French (e.g. 'evacuer'), then into Middle English and Modern English as 'evacuate' (verb) and 'evacuation' (noun).

Initially it meant 'to make empty' (to empty out); over time it broadened to include moving people or things out of danger or an area, leading to the modern primary sense of 'moving people to safety'.