World English Dictionary
-ium or (sometimes) -um
suffix forming nouns
1.  indicating a metallic element: platinum; barium
2.  (in chemistry) indicating groups forming positive ions: ammonium chloride; hydroxonium ion
3.  indicating a biological structure: syncytium
[New Latin, from Latin, from Greek -ion, diminutive suffix]
-um or (sometimes) -um
suffix forming nouns
[New Latin, from Latin, from Greek -ion, diminutive suffix]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Cite This Source
Explore Dictionary.com
Previous Definition: -ulous
Next Definition: -ure
Words Near: -um
More from Thesaurus.com
Synonyms and Antonyms for -um
More from Reference.com
Search for articles containing -um
More from Dictionary.com Translator
Dictionary.com Word FAQs

Dictionary.com presents 366 FAQs, incorporating some of the frequently asked questions from the past with newer queries.

Nearby Words
Copyright © 2014 Dictionary.com, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature