Absence of atmosphere or air in space CALLED?

A planet's atmosphere, by definition surrounds the planet.

As one leaves a planet's orbit (earth's orbit), one leaves the atmosphere.

That doesn't mean that space is completely devoid of everything. Pressures are low, but there are many cosmic particles, ions, solar winds, and cosmic radiation in space. However, the quantity of cosmic particles are so low that humans must use space suits and breath supplied oxygen.