[ rent-gen-ee-uhm, -jen-, ruhnt- ]
/ rɛntˈgɛn i əm, -ˈdʒɛn-, rʌnt- /
noun Chemistry, Physics.
a superheavy, synthetic radioactive element with a very short half-life. Symbol: Rg; atomic number: 111.
IS YOUR DESERT PLANT KNOWLEDGE SUCCULENT OR DRIED UP?
Cactus aficionados, don't get left in the dust with this quiz on desert plants. Find out if you have the knowledge to survive this prickly foray into the desert!
Question 1 of 7
This tall, horizontally branched cactus is probably the most recognizable cactus in Arizona. What is it called?
Formerly u·nu·nun·i·um [uh-nuh-nuhn-ee-uhm] /ə nəˈnʌn i əm/ , el·e·ment 111 .
Words nearby roentgenium
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020
Scientific definitions for roentgenium
[ rĕnt-gĕn′ē-əm, -jĕn′-, rŭnt-, rœnt-gĕn′- ]
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.