a. Resembling a diamond; made of, or abounding in, diamonds; as, a diamond chain; a diamond field. [ 1913 Webster ]

n. [ OE. diamaund, diamaunt, F. diamant, corrupted, fr. L. adamas, the hardest iron, steel, diamond, Gr. &unr_;. Perh. the corruption is due to the influence of Gr. &unr_; transparent. See Adamant, Tame. ] 1. A precious stone or gem excelling in brilliancy and beautiful play of prismatic colors, and remarkable for extreme hardness. [ 1913 Webster ]

☞ The diamond is native carbon in isometric crystals, often octahedrons with rounded edges. It is usually colorless, but some are yellow, green, blue, and even black. It is the hardest substance known. The diamond as found in nature (called a rough diamond) is cut, for use in jewelry, into various forms with many reflecting faces, or facets, by which its brilliancy is much increased. See Brilliant, Rose. Diamonds are said to be of the first water when very transparent, and of the second or third water as the transparency decreases. [ 1913 Webster ]

2. A geometrical figure, consisting of four equal straight lines, and having two of the interior angles acute and two obtuse; a rhombus; a lozenge. [ 1913 Webster ]

3. One of a suit of playing cards, stamped with the figure of a diamond. [ 1913 Webster ]

4. (Arch.) A pointed projection, like a four-sided pyramid, used for ornament in lines or groups. [ 1913 Webster ]

5. (Baseball) The infield; the square space, 90 feet on a side, having the bases at its angles. [ 1913 Webster ]

6. (Print.) The smallest kind of type in English printing, except that called brilliant, which is seldom seen. [ 1913 Webster ]

☞ This line is printed in the type called Diamond. [ 1913 Webster ]

Black diamond, coal; (Min.) See Carbonado. --
Bristol diamond. See Bristol stone, under Bristol. --
Diamond beetle (Zool.), a large South American weevil (Entimus imperialis), remarkable for its splendid luster and colors, due to minute brilliant scales. --
Diamond bird (Zool.), a small Australian bird (Pardalotus punctatus, family Ampelidæ.). It is black, with white spots. --
Diamond drill (Engin.), a rod or tube the end of which is set with black diamonds; -- used for perforating hard substances, esp. for boring in rock. --
Diamond finch (Zool.), a small Australian sparrow, often kept in a cage. Its sides are black, with conspicuous white spots, and the rump is bright carmine. --
Diamond groove (Iron Working), a groove of V-section in a roll. --
Diamond mortar (Chem.), a small steel mortar used for pulverizing hard substances. --
Diamond-point tool, a cutting tool whose point is diamond-shaped. --
Diamond snake (Zool.), a harmless snake of Australia (Morelia spilotes); the carpet snake. --
Glazier's diamond, a small diamond set in a glazier's tool, for cutting glass. [ 1913 Webster ]

n. (Zool.) The salt-marsh terrapin of the Atlantic coast (Malacoclemmys palustris). [ 1913 Webster ]

a. 1. Having figures like a diamond or lozenge. [ 1913 Webster ]

2. Adorned with diamonds; diamondized. Emerson. [ 1913 Webster ]

v. t. To set with diamonds; to adorn; to enrich. [ R. ] [ 1913 Webster ]

Diamondizing of your subject. B. Jonson. [ 1913 Webster ]

{ etc. } an anniversary celebrated upon the completion of sixty, or, according to some, seventy-five, years from the beginning of the event commemorated. [ Webster 1913 Suppl. ]

a. Shaped like a diamond or rhombus. [ 1913 Webster ]

. Delaware; -- a nickname alluding to its small size. [ Webster 1913 Suppl. ]

n. See regent diamond. [ 1913 Webster ]

. A famous diamond of fine quality, which weighs about 137 carats and is among the state jewels of France. It is so called from the Duke of Orleans, Regent of France, to whom it was sold in 1717 by Pitt the English Governor of Madras (whence also called the Pitt diamond), who bought it of an Indian merchant in 1701. [ Webster 1913 Suppl. ]