: extremely heavy
a superheavy discussion with his mother
: 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
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.
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