zirconia

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Cubic zirconia.

from The Century Dictionary.

• noun An oxid, ZrO, of the metal zirconium, resembling alumina in appearance. It is so hard as to scratch glass.
• noun This earth is now of industrial value as the chief material used in the ‘glower’ of the Nernst incandescent electric lamp. The glower commonly consists of about 85 per cent. zirconia and 15 per cent. yttria or mixed earths of that class.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Chem.) The oxide of zirconium (ZrO2), obtained as a white powder, and possessing both acid and basic properties. On account of its infusibility, and brilliant luminosity when incandescent, it is used as an ingredient of sticks for the Drummomd light.
• noun A colorless form of zirconia similar in appearance and refractivity to diamond, and used as a substitute for diamonds in inexpensive jewelry; -- also known by the acronym CZ.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun chemistry The oxide of zirconium, obtained as a white powder, and possessing both acid and basic properties. On account of its infusibility, and brilliant luminosity when incandescent, it is used as an ingredient of sticks for the Drummond light.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a white crystalline oxide; used in refractories and in insulation and abrasives and enamels and glazes