n. any of a range of reddish-brown minerals that are mixed phosphates of the lighter rare earth elements lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium and yttrium
the GNU version of the Collaborative International Dictionary of English
n. A mineral occurring usually in small isolated crystals, -- a phosphate of the cerium metals.
The Century Dictionary and Cyclopedia
n. A phosphate of the cerium metals, usually containing some thorium silicate.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a reddish-brown mineral containing rare earth metals; an important source of thorium and cerium
Word Usage
"Some of the country's beach sands contain monazite that yield thorium, which find application in fuels for nuclear reactors."