diamond

¹ American  

[dahy-muhnd, dahy-uh-] / ˈdaɪ mənd, ˈdaɪ ə- /

noun

1. a pure or nearly pure, extremely hard form of carbon, naturally crystallized in the isometric system.

2. a piece of this stone.

3. a transparent, flawless or almost flawless piece of this stone, especially when cut and polished, valued as a precious gem.

4. a ring or other piece of jewelry containing such a precious stone, especially an engagement ring.

5. a piece of this stone used in a drill or cutting tool.

6. a tool provided with such an uncut stone, used for cutting glass.

7. crystallized carbon, or a piece of it, artificially produced.

8. an equilateral quadrilateral, especially as placed with its diagonals vertical and horizontal; a lozenge or rhombus.

9. any rhombus-shaped figure or object oriented with its diagonals vertical and horizontal.

10. a red rhombus-shaped figure on a playing card.

11. a card of the suit bearing such figures.

12. (used with a singular or plural verb) diamonds, the suit so marked.

    Diamonds is trump. Diamonds are trump.

13. Baseball.

    1. the space enclosed by home plate and the three bases; infield.

    2. the entire playing field.

14. Printing. a 4½-point type of a size between brilliant and pearl.

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adjective

1. made of or set with a diamond or diamonds.

2. having the shape of a diamond.

   a dress with a diamond print.

3. indicating the 75th, or sometimes the 60th, event of a series, as a wedding anniversary.

verb (used with object)

1. to adorn with or as if with diamonds.

idioms

1. diamond in the rough, a person of fine character but lacking refined manners or graces.

Diamond ² American  

[dahy-muhnd, dahy-uh-] / ˈdaɪ mənd, ˈdaɪ ə- /

noun

1. Neil, born 1941, U.S. singer and songwriter.

2. Cape, a hill in Canada, in S Quebec, on the St. Lawrence River.

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diamond British  

/ ˈdaɪəmənd /

noun

1. 1. a colourless exceptionally hard mineral (but often tinted yellow, orange, blue, brown, or black by impurities), found in certain igneous rocks (esp the kimberlites of South Africa). It is used as a gemstone, as an abrasive, and on the working edges of cutting tools. Composition: carbon. Formula: C. Crystal structure: cubic

   2. ( as modifier )

      a diamond ring

2. geometry

   1. a figure having four sides of equal length forming two acute angles and two obtuse angles; rhombus

   2. (modifier) rhombic

3. 1. a red lozenge-shaped symbol on a playing card

   2. a card with one or more of these symbols or ( when plural ) the suit of cards so marked

4. baseball

   1. the whole playing field

   2. the square formed by the four bases

5. (formerly) a size of printer's type approximately equal to 4 1/ 2 point

6. a figurative name for coal

7. 1. an unpolished diamond

   2. a person of fine character who lacks refinement and polish

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verb

1. (tr) to decorate with or as with diamonds

diamond Scientific  

/ dī′ə-mənd /

1. A form of pure carbon that occurs naturally as a clear, cubic crystal and is the hardest of all known minerals. It often occurs as octahedrons with rounded edges and curved surfaces. Diamond forms under conditions of extreme temperature and pressure and is most commonly found in volcanic breccias and in alluvial deposits. Poorly formed diamonds are used in abrasives and in industrial cutting tools.

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Usage

What does diamond mean? A diamond is a clear gemstone known for its use in jewelry and its high price. The word diamond can also refer to the material, which is one of the hardest known substances. It has many practical and industrial applications, including for grinding and polishing—many drill bits have diamond tips, for example. Diamonds are perhaps the most popular gemstone used in jewelry. They are classified as precious gems, meaning that they have a high commercial value. They are often rated based on four main qualities: cut, color, clarity, and carat weight. Many cut diamonds are crystal clear, but sometimes they come in other transparent colors, including pink, yellow, and blue (like the famous Hope diamond). Some diamonds are synthetic—they’re manufactured in laboratories. The diamond is the traditional birthstone for the month of April. It’s associated with the zodiac signs Aries and Taurus. The word diamond is also used to refer to a shape (♦), like the one that’s used as one of the four “suits” on playing cards. Sometimes, it refers to a shape that looks like a cut diamond gem. This is how the word is used in baseball diamond. Diamond can be used as an adjective to describe things that include diamonds (as in a diamond necklace), are made of diamond (as in a diamond drill bit tip), or are diamond-shaped or diamond-patterned, among other things. The word diamond is sometimes used to describe a 75-year anniversary, as in It’s my grandparents’ diamond anniversary this year—I can’t believe they’ve been married for 75 years!Example: Look at her ring—that must be the biggest diamond I’ve ever seen!

Other Word Forms

• diamond-like adjective
• diamondlike adjective

Etymology

Origin of diamond

1275–1325; Middle English diamant < Old French < Vulgar Latin *diamant-, stem of *diamas, perhaps alteration of *adimas (> French aimant magnet, Old Provençal aziman diamond, magnet), for Latin adamas adamant, diamond

Explanation

A diamond is a valuable gemstone that's often used to make expensive jewelry. You might admire your friend's diamond earrings, but secretly wonder if they're real. An engagement ring is typically set with one or more diamonds. Diamonds used for jewelry are cut and polished, and they're evaluated for quality and price by weight, or carat, as well as by their cut, clarity, and color. Another kind of diamond is the geometrical shape, which is also seen on playing cards called diamonds, and echoed in the shape of a baseball field, also known as a diamond.

Example Sentences

Seven native rattlesnake species are in California, including the Mojave, Western diamondback, red diamond, Southern Pacific, Northern Pacific, Great Basin, and the speckled rattlesnake.

From Los Angeles Times • Mar. 23, 2026

“The Golden Pear Affair” revolves around two identical sisters, a stolen diamond and supporting roles for products from P&G’s Native personal-care line.

From The Wall Street Journal • Mar. 18, 2026

"Failure after failure, then we found something we weren't expecting in the mess -- a real diamond in the rough. And it is all thanks to a failed control experiment," Vahey said.

From Science Daily • Mar. 14, 2026

They include a diamond and emerald necklace Emperor Napoleon gave to his wife were stolen.

From BBC • Feb. 24, 2026

But the moment I step beyond the diamond bracelet, a loud boom echoes through the room as something crashes into the other side of the big red door.

From "Amari and the Night Brothers" by B.B. Alston

Related Words

• gem
• jewel
• rhinestone