osmium

noun

os·​mi·​um ˈäz-mē-əm 

: 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

Examples of osmium in a Sentence

Recent Examples on the Web

When the hydrothermal system was releasing osmium, the dominant plankton were species living in high-nutrient environments. —David Bressan, Forbes.com, 29 Apr. 2025

When the osmium returned to pre-impact levels, the plankton changed to species adapted to low-nutrient environments. —David Bressan, Forbes.com, 29 Apr. 2025

The study hinges on a chemical element called osmium, a metallic element common in asteroids. —David Bressan, Forbes.com, 29 Apr. 2025

While zircons from this time period have not yet been studied, Halverson notes that previous studies of snowball Earth have tracked the presence of iron, neodymium, and osmium in the geologic record. —Ars Technica, 28 Feb. 2025

Both elements belong to the same group of periodic metals known as platinum group metals (PGMs), which also includes ruthenium, rhodium, osmium and iridium. —Victor Rosario, Sacramento Bee, 26 Feb. 2025

What’s more, while gold is largely mined on its own (sometimes alongside copper and zinc), platinum is often mined along with a group that includes palladium, rhodium and osmium. —Ryan Ermey, CNBC, 18 Oct. 2024

In addition to ruthenium, iridium, osmium, platinum, platinum, and rhodium are rare on Earth, but common in meteorites, so a global distribution is consistent with initiating a mass extinction. —Andrew Paul, Popular Science, 15 Aug. 2024

Platinum is part of the six platinum-group metals (PGM), including palladium, iridium, rhodium, ruthenium, and osmium. —Laxmi Corp, The Salt Lake Tribune, 11 Sep. 2023

Word History

Etymology

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).

First Known Use

1804, in the meaning defined above

Phrases Containing osmium

• osmium tetroxide

Kids Definition

osmium

noun

os·​mi·​um ˈäz-mē-əm 

: a hard brittle blue-gray or blue-black metallic element with a high melting point that is the heaviest metal known see element

Medical Definition

osmium

noun

os·​mi·​um ˈäz-mē-əm 

: 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