Wiktionary
degree of ionization
n. (context chemistry English) the ratio of the number of ions of a solute to the total number of molecules of that solute in a solution
Wikipedia
Degree of ionization
The degree of ionization (also known as ionization yield in the literature) refers to the proportion of neutral particles, such as those in a gas or aqueous solution, that are ionized to charged particles. A low degree of ionization is sometimes called partially ionized, and a very high degree of ionization as fully ionized.
Ionization refers to the process whereby an atom or molecule loses an electron, resulting in two oppositely charged particles, (1) a negatively charged electron and (2) a positively charged ion.
Usage examples of "degree of ionization".
The degree of ionization in the room was constantly changing, too.