ununennium/uːnuːnˈɛniːəm/EtymologySystematic element name, from un- + un- + enn- + -ium.nounThe systematic element name for the (as yet undiscovered) chemical element with atomic number 119 (symbol Uue).“Element 119: Ununennium (Uue) This has yet to be reported. From its position in the periodic table, in group 1 below francium, this element should have the physical properties of an alkali metal and, were it long-lived enough, the element should display the singly-charged ion M⁺ as its most favoured chemical state.”