Why is it called a vacuum?

Why is it called a vacuum comes from physics definition and function of the device. The word vacuum comes from Latin vacuus meaning empty, void, or free from matter. In physics, a vacuum is space with no matter or air, or with very low pressure. A vacuum cleaner is called that because it works by creating a partial vacuum inside its chamber using a fan or motor that lowers air pressure, causing outside air at higher pressure to rush in carrying dirt and dust into bag or bin. The first vacuum cleaners in early 1900s were called vacuum cleaners because they used suction created by vacuum, as opposed to earlier carpet sweepers that used brushes. So name describes operating principle rather than what it cleans. It creates empty space that must be filled, thus pulling debris. The term vacuum cleaner distinguishes from other cleaners that use water or brushes. Even modern vacuums that use cyclonic separation still create low pressure region, so vacuum remains accurate description. So called vacuum because it uses vacuum pressure difference to suck up dirt from surfaces into collection container, emptying space of dust.