n. Symbol Sg An artificially produced radioactive element with atomic number 106 that has only been produced in trace amounts. The isotope with mass number 266 has the longest confirmed half-life (21 seconds), although heavier isotopes with longer half-lives have been reported. See Periodic Table. [After Glenn Theodore Seaborg.] |
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.