1. the fifth day of the week; the fourth working day • Syn: Thursday • Hypernyms: weekday 2. 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: thorium, atomic number 90 • Derivationally related forms: thoriate (for: thorium) • Hypernyms: metallic element, metal • Hyponyms: thorium-228, radiothorium • Substance Holonyms: monazite, thorite
