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a. Action or process: completion.
b. Result of an action or process: indention.
2. State or condition: dehydration.

[Middle English, from Old French, from Latin -iō, -iōn-, n. suff.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


suffix forming nouns
indicating an action, process, or state: creation; objection. Compare -ation, -tion
[from Latin -iōn-, -io]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈaɪ ən, ˈaɪ ɒn)

1. an atom or atom group electrically charged by the loss or gain of electrons, represented by a plus or a minus sign, as a cation (Na + , Ca + + ) or anion (Cl).
2. one of the electrically charged particles formed in a gas by electric discharge.
[< Greek ión going, neuter present participle of iénai to go; term introduced by Michael Faraday in 1834]
i•on′ic, adj.


a suffix, appearing in words of Latin origin, denoting action or condition, used to form nouns from stems of adjectives (communion; union) and verbs (legion; opinion; suspicion).
Compare -tion.
[Middle English -ioun < Anglo-French < Latin -iōnem, acc. of -iō suffix forming nouns]


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