n. One of the elements of an electrolyte, or compound body undergoing electrolyzation.n. A suffix in abstract nouns (many also used as concrete) of Latin origin, as in legion, opinion, option, region, religion, suspicion, communion, union, etc.n. A similar suffix occurring in a few concrete nouns designating persons or things, as in centurion, histrion, union (a pearl), onion, pavilion, etc.n. An abbreviation of longitude.n. In physical chemistry, one of the particles, bearing electric charges, which carry electric currents through the air or other gas. See electron, 2.n. In physical chemistry, the word ion added, as a suffix, to the abbreviated name of an atom or radical to form a name for the atom or radical in the ionic state: thus chlorion means an atom of chlorin in the ionic condition; cuproion or cupriion, the ion of univalent and of bivalent copper.n. An abbreviation of Ionic.