seaborgium Syllabification: (sea·bor·gi·um)Pronunciation: /sēˈbôrgēəm/Definition of seaborgium noun the chemical element of atomic number 106, a very unstable element made by high-energy atomic collisions. (Symbol: Sg)Origin:modern Latin, named after G. Seaborg (see Seaborg, Glenn)seaborgium in other Oxford dictionaries Definition of seaborgium in the British & World English dictionary