a pure or nearly pure, extremely hard form of carbon, naturally crystallized in the isometric system.
a piece of this stone.
a transparent, flawless or almost flawless piece of this stone, especially when cut and polished, valued as a precious gem.
a ring or other piece of jewelry containing such a precious stone, especially an engagement ring.
a piece of this stone used in a drill or cutting tool.
a tool provided with such an uncut stone, used for cutting glass.
crystallized carbon, or a piece of it, artificially produced.
an equilateral quadrilateral, especially as placed with its diagonals vertical and horizontal; a lozenge or rhombus.
any rhombus-shaped figure or object oriented with its diagonals vertical and horizontal.
a red rhombus-shaped figure on a playing card.
a card of the suit bearing such figures.
(used with a singular or plural verb) diamonds, the suit so marked.
Diamonds is trump. Diamonds are trump.
Baseball.
the space enclosed by home plate and the three bases; infield.
the entire playing field.
Printing. a 4½-point type of a size between brilliant and pearl.
made of or set with a diamond or diamonds.
having the shape of a diamond.
a dress with a diamond print.
indicating the 75th, or sometimes the 60th, event of a series, as a wedding anniversary.
Neil, born 1941, U.S. singer and songwriter.
Cape, a hill in Canada, in S Quebec, on the St. Lawrence River.
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
( as modifier )
a diamond ring
geometry
a figure having four sides of equal length forming two acute angles and two obtuse angles; rhombus
(modifier) rhombic
a red lozenge-shaped symbol on a playing card
a card with one or more of these symbols or ( when plural ) the suit of cards so marked
baseball
the whole playing field
the square formed by the four bases
(formerly) a size of printer's type approximately equal to 4 1/ 2 point
a figurative name for coal
an unpolished diamond
a person of fine character who lacks refinement and polish
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!
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
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.
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Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
He’s also multi-talented on the diamond, hitting a double and triple, getting three RBIs, making several tough plays at third base and pitching one inning in relief during a 7-2 victory over the Panthers.
From Los Angeles Times • May 23, 2026
The fancy vivid blue-green diamond is triangular in shape and "the size of the nail on your smallest finger" according to Fawcett.
From Barron's • May 13, 2026
Jones, who arrived at the scene with his partner a few minutes behind the others, was seen running to the front of the diamond formation without being ordered to do so.
From Los Angeles Times • May 7, 2026
It’s my fatherly nudge to do something that they’re a little nervous or apprehensive about, like the double black diamond or even trying a new food.
From The Wall Street Journal • May 4, 2026
In the light of the bonfire, Jeremy could see that the stone set in the ring's top was a tear-shaped diamond.
From "Jeremy Thatcher, Dragon Hatcher" by Bruce Coville
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
