from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An artificially produced radioactive element with atomic number 109 whose most long-lived isotopes have mass numbers of 266 and 268 with half-lives of 3.4 milliseconds and 70 milliseconds, respectively. Also called unnilennium. See Table at element.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A transuranic chemical element (symbol Mt) with atomic number 109.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a radioactive transuranic element
After Lise Meitner.(American Heritage® Dictionary of the English Language, Fourth Edition)
Named for Lise Meitner (Wiktionary)