os·​mi·​um | \ ˈäz-mē-əm How to pronounce osmium (audio) \

Definition of osmium

: a blue-gray or blue-black hard brittle very heavy polyvalent metallic element with a high melting point that is used especially as a catalyst and in hard alloys — see Chemical Elements Table

First Known Use of osmium

1804, in the meaning defined above

History and Etymology for osmium

Greek osmḗ "smell, odor" + -ium; osmḗ going back to *od-s-mā, noun derivative from the base of ózein "to smell, give off an odor" — more at odor

Note: The word osmium was introduced by the English chemist Smithson Tennant (1761-1815) in Philosophical Transactions of the Royal Society, 1804, Part II, p. 416: "When the alkaline solution [obtained by dissolving impure platinum] is first formed, by adding water to the dry alkaline mass in the crucible, a pungent and peculiar smell is immediately perceived. This smell, as I afterwards discovered, arises from the extrication of a very volatile metallic oxide; and, as this smell is one of its most distinguishing characters, I should on that account incline to call the metal Osmium." In the same report Tennant discussed and named the element iridium (see iridium).

Keep scrolling for more

Learn More about osmium

Time Traveler for osmium

Time Traveler

The first known use of osmium was in 1804

See more words from the same year

Statistics for osmium

Cite this Entry

“Osmium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/osmium. Accessed 20 Jan. 2021.

Keep scrolling for more

More Definitions for osmium


os·​mi·​um | \ ˈäz-mē-əm How to pronounce osmium (audio) \

Medical Definition of osmium

: a hard brittle blue-gray or blue-black polyvalent metallic element of the platinum group with a high melting point that is the heaviest metal known and that is used especially as a catalyst and in hard alloys symbol Os — see Chemical Elements Table

More from Merriam-Webster on osmium

Britannica.com: Encyclopedia article about osmium

Comments on osmium

What made you want to look up osmium? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Words of Snow and Ice Quiz

  • image1037863653
  • Which of the following refers to thin, bending ice, or to the act of running over such ice?
True or False

Test your knowledge - and maybe learn something along the way.


Anagram puzzles meet word search.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!