An Etymological Dictionary of Astronomy and Astrophysics

In physics, a gas in which an important fraction of the atoms is ionized, so that the electrons and ions are separately free. Plasma, often described as the fourth state of matter, occurs at extremely high temperatures, as in the interiors of stars, in fusion reactors, and in the interstellar medium ionized by hot stars.

Etymology (EN): From L.L. plasma, from Gk. plasma “something molded or formed,” from plassein “to mold,” originally “to spread thin.”

Etymology (PE): Plâsmâ, loan from Fr.