Answer: In plain English, nonion is a substance that does not ionize in water. Ionization is the process by which electrolytes in a specific solvent (e.g. water, alcohol) are separated into charged ions that can move freely. For example, daily salt, sodium chloride (NaCl), dissolves in water and ionizes to produce freely moving sodium ions with positive charges and chloride ions with negative charges. In other words, HPMC in water does not dissociate into charged ions, but exists as molecules.