n. [ Zircon + oid. ] (Crystallog.) A double eight-sided pyramid, a form common with tetragonal crystals; -- so called because this form often occurs in crystals of zircon. [ 1913 Webster ]

n. [ NL. ] (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. [ 1913 Webster ]

cubic zirconia. 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. [ PJC ]