diamond

1. (uncountable) A glimmering glass-like mineral that is an allotrope of carbon in which each atom is surrounded by four others in the form of a tetrahedron.Examples: "The saw is coated with diamond."; "synthetic diamond"uncountable

2. (heraldry) Sable, when blazoning by precious stones.Examples: "Elphingston. Pearl a Chevron Diamond between three Boars Heads Eraz'd Ruby, arm'd of the first. / Eymouth. Diamond a Lyon Rampant Pearl, on a Canton of the 2d, a Cross Ruby."; "The Field is Ruby, on a Bend Topaz, three Martlets Diamond. The Armes of the most Noble and Puissant Lord, Edward Brabazon, Earl of Meath, and Baron of Atherdee in the Kingdom of Ireland. His Lordship's Atchievements are Quarterly of sixteen Coats. 1. Brabazon, as above. 2. Diamond, on a Chevron between three Pickaxes Pearl, as many Mullets Ruby, by the Name of Mosley. 3. Saphire, ten Bezants, 4, 3, 2, 1, by the Bisset."; "Pearl, an Eagle, Diamond, between three Crosses Patee, Ruby, for Morrys."countableuncountable

3. (geometry) A rhombus, especially when oriented so that its longer axis is vertical.Examples: "An adder writhes out of the bush, I can see the diamonds on its back; it shrithes across the sandy soil, and bites the right foot of one of the knights."Synonyms: lozenge, rhombcountableuncountable

4. (geometry) The polyiamond made up of two triangles.Synonyms: 2-iamondcountableuncountable

5. (baseball) The entire field of play used in the game.Synonyms: ball field, baseball fieldcountableuncountable

6. (baseball) The infield of a baseball field.Examples: "The teams met on the diamond."Synonyms: baseball diamond, infieldAntonyms: outfieldcountableuncountable