The American Heritage® Dictionary of the English Language, 4th Edition
n. A natural, variously colored calcium fluoride phosphate, Ca5F(PO4)3, with chlorine, hydroxyl, or carbonate sometimes replacing the fluoride. It is a source of phosphorus for plants and is used in the manufacture of fertilizers.
n. A calcium fluoride phosphate of variable composition, sometimes used in the manufacture of fertilizer.
the GNU version of the Collaborative International Dictionary of English
n. Native phosphate of lime, occurring usually in six-sided prisms, color often pale green, transparent or translucent.
The Century Dictionary and Cyclopedia
n. Native calcium phosphate with calcium fluorid or chlorid, generally crystallized in hexagonal prisms, which are sometimes low or even tabular, sometimes elongated, and occasionally of great size.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a common complex mineral consisting of calcium fluoride phosphate or calcium chloride phosphate; a source of phosphorus
Word Usage
"And one of the properties of [hydroxy] apatite is that you can have supersaturated solutions of calcium and phosphate that can be maintained quite stably."