A partial vacuum can also be referred to as a low pressure environment, reduced pressure, or negative pressure. It is an area where the pressure is lower than the surrounding atmosphere. Another synonym for partial vacuum is an "incomplete vacuum." This is because the air density in a partial vacuum is still present, just at a lower level than usual. Other words that describe a partial vacuum include rarefied, depleted, or diminished. In scientific terms, a partial vacuum is an area where the gas pressure is lower than atmospheric pressure, which can be achieved by removing air from an enclosed space using a vacuum pump.