Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- The symbol for element 115.
- An artificially produced radioactive element whose most stable confirmed isotopes have mass numbers of 287 and 288 and half-lives of less than one second. Also called ununpentium See Periodic Table.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.