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
Roentgenium, after a modern physicist renamed roentgenium by the General Assembly, was originally discovered in 1994 when a team at GSI created three atoms of the element, about a month after their discovery of darmstadtium, on Dec. 8.
Elements 110, 111 and 112 have been named darmstadtium (Ds), roentgenium (Rg) and copernicium (Cn).
The previous heavyweight winners were copernicium (285) and roentgenium (272).
I'll give americium a pass since it goes without saying America rules, but what the hell is roentgenium named after?
The isotope with 177 neutrons decays down to dubnium (atomic number 105), whereas the isotope with 176 neutrons decays down to roentgenium (atomic number 111).