- noun a very hard, clear, precious stone
- noun one of the red sets in a pack of cards, shaped like a square leaning to one side
- noun a very hard transparent crystalline form of carbon, used as a gemstone, in abrasives and in cutting tools
- An allotropic form of the chemical element carbon, occurring as crystals. It is the hardest substance known, and as such has an assigned value of 10 on the Mohs scale. It is a precious stone, has extremely high thermal conductivity, a high refractive index, and may be transparent, translucent, or colored. Its applications include its use in cutting and grinding tools, optical windows, lasers, and semiconductors.
- noun a tactical formation in the form of a square, with one corner pointing in the direction of advance
- noun a tactical formation, with one sub-unit leading as point, followed by two sub-units abreast of each other, followed by one sub-unit centre rear
- noun an old size of type, equivalent to 4 1/2 pt
- adjective first-rate, superb, admirable. A London working-class and underworld term, often heard in the appreciative phrase ‘a diamond geezer’.
- noun the area of a baseball field bounded by home plate and the three bases
- noun an area for playing baseball including the infield and the outfield
Origin & History of “diamond”
Diamond is an alteration of adamant, a rather archaic term which nowadays refers to hard substances in general, but formerly was also used specifically for ‘diamond’. The alteration appears to have come about in Latin of post-classical times: adamant- (stem of Latin adamas) evidently became vulgar Latin *adimant- (source of French aimant ‘magnet’), which appears to have opened the way to confusion, or at least association, with words beginning dia-. The result was medieval Latin diamant-, which passed into English via Old French diamant.