a radioactive chemical element with a very short half-life: a transactinide produced by bombarding lead with high-energy nuclear particles: symbol, Hs: at. no., 108
See hassium in American Heritage Dictionary 4
(häˈsē-əm)
noun Symbol Hs
An artificially produced radioactive element with atomic number 108 whose most long-lived isotopes have mass numbers of 264 and 265 with half-lives of 0.08 milliseconds and 2 milliseconds, respectively. Also called unniloctium. See Table at element.