osmous definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
designating or of chemical compounds in which osmium has a lower valence than in the corresponding osmic compounds
osmous definition by American Heritage Dictionary
Of, relating to, or containing osmium in a compound with a valence lower than that in a comparable osmic compound.
Origin: osm(ium) + -ous.