Found 2 items, similar to thorium.
English → English (WordNet) Definition: thorium thorium n : a soft silvery-white tetravalent radioactive metallic element; isotope 232 is used as a power source in nuclear reactors; occurs in thorite and in monazite sands [syn: Th, atomic number 90]
English → English (gcide) Definition: Thorium Thorium \Tho"ri*um\, n. [NL. See Thorite.] (Chem.) A metallic element found in certain rare minerals, as thorite, pyrochlore, monazite, etc., and isolated as an infusible gray metallic powder which burns in the air and forms thoria; -- formerly called also thorinum. Symbol Th. Atomic weight 232.0. [1913 Webster]