di·a·mond (d-mnd, dmnd)
n.
1. An extremely hard, highly refractive crystalline form of carbon that is usually colorless and is used as a gemstone and in abrasives, cutting tools, and other applications.
2. A piece of jewelry containing such a gemstone.
3. A figure with four equal sides forming two inner obtuse angles and two inner acute angles; a rhombus or lozenge.