This page is about the physical properties of gas as a state of matter. For the uses of gases, and other meanings, see Gas (disambiguation). » As a noun in the English language, a gas is one of three classical states of matter. Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point, boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized that they… (More on Gaseous)