Degree of ionization
The degree of ionization 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. the ratio of the number of ions of a solute to the total number of molecules of that solute in a solution .we can say also like "Very high degree of ionization is known as fully ionized."
The degree of dissociation α (sometimes also degree of ionization), is a way of representing the strength of an acid. It is defined as the ratio of the number of ionized molecules and the number of molecules dissolved in water. It can be represented as a decimal number or as a percentage. One can classify strong acids as those having ionization degrees above 30%, weak acids as those with α below 30%, and the rest as moderate acids, at a specified molar concentration.