a radioactive chemical element with a very short half-life: a transactinide produced by bombarding californium or lead with high-energy nuclear particles: symbol, Sg; at. no., 106
See seaborgium in American Heritage Dictionary 4
(sē-bôrˈgē-əm)
noun Symbol Sg
An artificially produced radioactive element with atomic number 106 whose most long-lived isotopes have mass numbers 259, 261, 263, 265, and 266 with half-lives of 0.9, 0.23, 0.8, 16, and 20 seconds, respectively. Also called unnilhexium. See Table at element.