Vacuum
Term
This is a space where the gas pressure is lower. An absolute vacuum, where there are no atoms and molecules at all, is unattainable. It is distinguished between low vacuum >10–2 Pa, medium vacuum 10–2–10–7 Pa, and high vacuum <10–7 Pa.
Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė