A space which is entirely devoid of matter is called a vacuum in scientific terms.
The word comes from the Latin vacuum, meaning “empty” or “void.” In classical physics, a perfect vacuum contains no particles or material substance. Real-world vacuums are only approximations: laboratory chambers and outer space still contain tiny amounts of gas, radiation, or other particles.
The idea of a vacuum was debated for centuries. Aristotle argued that nature could not permit empty space, an idea summarized as horror vacui, or “nature abhors a vacuum.” In the 1640s, Evangelista Torricelli’s mercury-barometer experiments provided strong evidence that a vacuum could exist above a column of liquid.
A common mix-up is calling outer space a perfect vacuum. It is actually an extremely thin vacuum, containing sparse hydrogen, helium, dust, radiation, and neutrinos. In quantum physics, even a vacuum is not simply “nothing”: the vacuum state is the lowest-energy state of fields and can exhibit measurable quantum effects.