superheavy

adjective

su·​per·​heavy ˌsü-pər-ˈhe-vē 

: extremely heavy

superheavy furniture

superheavy traffic

a superheavy discussion with his mother

especially, chemistry : relating to or being a chemical element with a greater atomic mass than that of uranium

The existence of superheavy elements, those with many more protons than uranium (proton number 92), was predicted more than 40 years ago.

—Georg Bollen

superheavy noun

plural superheavies

In February the world was treated to a transcontinental eureka moment: Scientists … announced they had discovered two new chemical elements. Called superheavies because of their large atomic mass, elements 113 and 115 lasted little more than a second.

—Elizabeth Svoboda

Examples of superheavy in a Sentence

Recent Examples on the Web

In this new model, superheavy dark matter particles could be trapped by exoplanets, losing energy and drifting toward that world's core. —Robert Lea, Space.com, 25 Aug. 2025

The superheavy Yenisei rocket intended for the nation’s lunar missions had reached a critical milestone, the approval of its preliminary design, in late 2019. —Eugene Gerden, Scientific American, 30 June 2025

Firing a calcium beam at different targets is how the superheavy elements 112 to 118 were first synthesized. —Michael Irving, New Atlas, 25 July 2024

Word History

First Known Use

1822, in the meaning defined above

Rhymes for superheavy

• bevy
• chevy
• heavy
• levee
• levy
• replevy