[ rent-gen-ee-uhm, -jen-, ruhnt- ]

nounChemistry, Physics.
  1. a superheavy, synthetic radioactive element with a very short half-life. Symbol: Rg; atomic number: 111.

Origin of roentgenium

First recorded in 2000–05; named after German physicist Wilhelm Konrad Roentgen.
  • Formerly u·nu·nun·i·um [uh-nuh-nuhn-ee-uhm], /ə nəˈnʌn i əm/, el·e·ment 111 .

Words Nearby roentgenium Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Scientific definitions for roentgenium


[ rĕnt-gĕnē-əm, -jĕn-, rŭnt-, rœnt-gĕn- ]

  1. An artificially produced radioactive element with a mass number of 280. Its most stable known isotope has a half-life of 3.6 seconds. Atomic number 111. See Periodic Table.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.