- A thin fluid, such as air, capable of indefinite expansion but convertible by compression and cold into a liquid and, eventually, a solid.
- In clinical practice, a liquid entirely in its vapor phase at one atmosphere of pressure because ambient temperature is above its boiling point.
[coined by J.B. van Helmont, Flemish chemist and physician, 1579–1644]
© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.