-onium

Origin of -onium

extracted from ammonium
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

-onium in Medicine

-onium

suff.
  1. Containing a positively charged radical:carbonium.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.