| NOUN | substance | Rg, roentgenium, element 111, atomic number 111 | a radioactive transuranic element |
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| Meaning | A radioactive transuranic element. | |
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| Synonyms | roentgenium, element 111, atomic number 111 | |
| Broader | chemical element, element | Any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter |