one of the electrically charged particles formed in a gas by electric discharge or the like. Definition of ion_2 suffix in Oxford Advanced Learner's Dictionary. All rights reserved. In the word 'slowly…. Origin of -tion. From Old English, meaning a ‘fortified enclosure’. -ion word-forming element attached to verbs, making nouns of state, condition, or action, from French -ion or directly from Latin -ionem (nominative -io , genitive -ionis ), common suffix forming abstract nouns from verbs. the eponymous ancestor of the Ionians: a son of Apollo and Creusa who is abandoned by his mother but returns to become an attendant in Apollo's temple at Delphi. “Affect” vs. “Effect”: Use The Correct Word Every Time. Found 8160 words that end in ion. Learn suffix ion with free interactive flashcards. by Euripides.