Home › Words › U › untritriumuntritriumuntritrium · noun — the systematic element name for the (as yet undiscovered) chemical element with atomic number 133 (symbol Utt).Definition from Wiktionary (CC BY-SA 3.0).EtymologySystematic element name, from un- + tri- + tri- + -ium.nounThe systematic element name for the (as yet undiscovered) chemical element with atomic number 133 (symbol Utt).Definitions & examples from Wiktionary (CC BY-SA 3.0).