Vacuum is space that is devoid o matter. The wird stems frae the Laitin adjective vacuus for "vacant" or "void". An approximation tae such vacuum is a region wi a gaseous pressur much less than atmospheric pressur. Pheesicists eften discuss ideal test results that would occur in a perfect vacuum, which thay sometimes simply call "vacuum" or free space, an uise the term pairtial vacuum tae refer tae an actual imperfect vacuum as ane micht hae in a laboratory or in space. The Laitin term in vacuo is uised tae describe an object as bein in whit would itherwise be a vacuum.