1. extremely heavy in weight
2. having an atomic number greater than that of the heaviest naturally occurring elements
Usage: chemistry; physics

Examples

• The ultraheavy machinery required a special crane to lift it.
• Scientists created ultraheavy elements in the laboratory.
• The ultraheavy backpack made hiking extremely difficult.
• Researchers study ultraheavy atomic nuclei to understand matter.
• The ultraheavy steel beam could support enormous loads.
• Ultraheavy elements are highly unstable and decay quickly.