from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun The
systematic element namefor the (as yet unconfirmed) chemical element with atomic number113 (symbol Uut)
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun a radioactive transuranic element
from The American Heritage® Dictionary of the English Language, 4th Edition
[Latin ūnus, one; see oi-no- in Indo-European roots + Latin ūnus + Latin and Greek tri-, tri- + –ium (in reference to its atomic number).]
Only eight atoms of ununtrium have been observed to date.