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)