a suffix, appearing in words of Latin origin, denoting action or condition, used in Latin and in English to form nouns from stems of Latin adjectives (communion; union), verbs (legion; opinion), and especially past participles (allusion; creation; fusion; notion; torsion).

Nearby words

  1. -in,
  2. -ina,
  3. -inae,
  4. -ine,
  5. -ing,
  6. -ior,
  7. -ious,
  8. -isation,
  9. -ise,
  10. -ish

Compare -cion, -xion.

Origin of -ion

< Latin -iōn- (stem of -iō) suffix forming nouns, especially on past participle stems; replacing Middle English -ioun < Anglo-French < Latin -iōn-

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for -ion


suffix forming nouns

indicating an action, process, or statecreation; objection Compare -ation, -tion

Word Origin for -ion

from Latin -iōn-, -io

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for -ion


suffix forming nouns of state, condition, or action from verbs, from Latin -ionem (nominative -io), sometimes via French -ion.

Online Etymology Dictionary, © 2010 Douglas Harper