from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. An artificially produced radioactive element with atomic number 111 and a mass number of 280, whose most stable known isotope has a half-life of 3.6 seconds. See Table at element.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A transuranic chemical element (symbol Rg) with atomic number 111.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a radioactive transuranic element


After Wilhelm Konrad Roentgen.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Surname of Wilhelm Roentgen + -ium (Wiktionary)



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