/thawr"ee euh nuyt', thohr"-/ , n.
a rare mineral, mainly thoria, ThO 2 , but also containing uranium, cerium, and other rare-earth metals, occurring in small, black, cubic crystals: notable for its radioactivity and used as a minor source of thorium.
[ 1900-05; thorian (THORI(A) + -AN) + -ITE 1 ]