from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun An extremely hard, highly refractive crystalline form of carbon that is usually colorless and is used as a gemstone and in abrasives, cutting tools, and other applications.
  • noun A piece of jewelry containing such a gemstone.
  • noun A rhombus, particularly when oriented so that one of its diagonals is vertical and the other is horizontal.
  • noun A red, lozenge-shaped figure on certain playing cards.
  • noun A playing card with this figure.
  • noun The suit of cards represented by this figure.
  • noun The infield.
  • noun The whole playing field.
  • adjective Of or relating to a 60th or 75th anniversary.
  • transitive verb To adorn with diamonds.
  • idiom (diamond in the rough) One having exceptionally good qualities or the potential for greatness but lacking polish and refinement.

from The Century Dictionary.

  • To set or decorate with diamonds.
  • noun Adamant; steel, or some imaginary substance of extreme hardness or impenetrability.
  • noun A precious stone, distinguished from all others by being combustible and by its extreme hardness, as well as by its superior refractive and dispersive power.
  • noun A geometrical figure bounded by four equal straight lines forming two acute and two obtuse angles; a rhomb; a lozenge; specifically, such a figure printed in red on a playing-card.
  • noun A playing-card stamped with one or more red lozenge-shaped figures.
  • noun A tool armed with a diamond, used for cutting glass.
  • noun In base-ball, the square space inclosed within the four bases.
  • noun In heraldry, the tincture black in blazoning by means of precious stones.
  • noun The smallest size of printing-type in common use; a size smaller than pearl. Brilliant, very rarely used, is the only regular size below it.
  • noun This line is printed in diamond.
  • noun Mineral coal, as consisting, like diamonds, of carbon.
  • Resembling a diamond; consisting of diamonds; set with a diamond or diamonds: as, a diamond luster; a diamond necklace; a diamond ring.
  • Lozenge-shaped; rhombic: as, diamond window-panes.
  • Having rhomboid figures or markings: as, the diamond rattlesnake.

from the GNU version of the Collaborative International Dictionary of English.

  • adjective Resembling a diamond; made of, or abounding in, diamonds
  • noun A precious stone or gem excelling in brilliancy and beautiful play of prismatic colors, and remarkable for extreme hardness.
  • noun A geometrical figure, consisting of four equal straight lines, and having two of the interior angles acute and two obtuse; a rhombus; a lozenge.
  • noun One of a suit of playing cards, stamped with the figure of a diamond.
  • noun (Arch.) A pointed projection, like a four-sided pyramid, used for ornament in lines or groups.
  • noun (Baseball) The infield; the square space, 90 feet on a side, having the bases at its angles.
  • noun (Print.) The smallest kind of type in English printing, except that called brilliant, which is seldom seen.
  • noun coal; (Min.) See Carbonado.
  • noun See Bristol stone, under Bristol.
  • noun (Zoöl.) a large South American weevil (Entimus imperialis), remarkable for its splendid luster and colors, due to minute brilliant scales.
  • noun (Zoöl.) a small Australian bird (Pardalotus punctatus, family Ampelidæ.). It is black, with white spots.
  • noun (Engin.) a rod or tube the end of which is set with black diamonds; -- used for perforating hard substances, esp. for boring in rock.
  • noun (Zoöl.) a small Australian sparrow, often kept in a cage. Its sides are black, with conspicuous white spots, and the rump is bright carmine.
  • noun (Iron Working) a groove of V-section in a roll.
  • noun (Chem.) a small steel mortar used for pulverizing hard substances.
  • noun a cutting tool whose point is diamond-shaped.
  • noun (Zoöl.) a harmless snake of Australia (Morelia spilotes); the carpet snake.
  • noun a small diamond set in a glazier's tool, for cutting glass.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun 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.
  • noun A gemstone made from this mineral.
  • noun A ring containing a diamond.
  • noun A very pale blue color/colour.


from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English diamaunt, from Old French diamant, from Medieval Latin diamās, diamant-, alteration of Latin adamās; see adamant.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Old French diamant, from Late Latin diamas, from Latin adamas, from Ancient Greek ἀδάμας (adámas, "invincible, untamed; hard substance"), from ἀ- (a-, "un-") + δαμάζω (damázo, "to overpower, tame, conquer").


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  • -- The real identity of the two words explains Milton’s use of ‘diamond’ in _Paradise Lost_, b. 7; and also in that sublime passage in his _Apology for Smectymnuus_: “Then zeal, whose substance is ethereal, arming in complete _diamond_”.

    English Past and Present Richard Chenevix Trench 1846

  • I didn't know that the word diamond comes from the Greek word "Adamas" which means unconquerable.

    Bisaya Bloggers 2009

  • Dayzatari say that diamonds are the thoughts of stars, fallen to earth, and the Pelorian name for diamond translates as "starthought."

    The Lore of Gloranthan Gems and Near-Gems by Martin R. Crim Part II 1992

  • Their trip to the crystal leads to the discovery that the diamond is actually hollow and harbors an alternate Earth.

    REVIEW: The Crystal Cosmos by Rhys Hughes 2008

  • I'll tell you, that very first shot, we got an amazing, amazing photo of what they call the diamond ring.

    CNN Transcript Jul 22, 2009 2009

  • If you wait another five minutes on this tape, you'll see what we call the diamond ring.

    CNN Transcript Aug 1, 2008 2008

  • These patrol men should have had a lot more training now, been able to gone into the school, been able to move into what we call a diamond formation, where the actual patrol officers stack up in three-man teams and begin a methodical search of the entire building going directly to the threat, not actually waiting outside the school which is what we saw in Columbine.

    CNN Transcript Apr 16, 2007 2007

  • Since those days Mr. Menpes has continued to draw from photographs, and -- the base of his artistic education being deficient from the first -- the result of his long abstention from Nature is apparent, even to the least critical, in the some hundred and seventy paintings, etchings, and what he calls diamond-points on ivory, on exhibition at

    Modern Painting 1892

  • Mr Cameron's inner team is settled in what he calls a diamond formation, with Andy Coulson, the Essex man, on the right wing, his ideas guru Steve Hilton providing the empathy and George Osborne providing the unshakeable will to win. news, business, sport, the Daily Telegraph newspaper, Sunday Telegraph 2009

  • Mr Cameron's inner team is settled in what he calls a diamond formation, with Andy Coulson, the Essex man, on the right wing, his ideas guru Steve Hilton providing the empathy and George Osborne providing the unshakeable will to win. news, business, sport, the Daily Telegraph newspaper, Sunday Telegraph 2009


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  • A mostly unnoticed marking on many tape measures in the United States, the diamond marks a distance unit of exactly 8/5 feet (19.2 inches or 48.768 centimeters). The marking is used by carpenters to place 5 studs, floor joists, etc., within a distance of 8 feet.

    November 8, 2007

  • I...I...holy crapple, reesetee. There is just no end to the wonders of this list.

    November 8, 2007

  • Isn't it amazing? I've been dying to go home and look at my tape measure!

    November 8, 2007

  • What's up with the "official" definition up there, using the word itself in the definition? Isn't that a federal offense?!

    Also... this is really cool. I wonder why they named it "diamond" and not, say, "hayrick"?

    November 8, 2007

  • Reesetee: That's exactly what I did, and there are diamonds all over it. How come I never even wondered what those were for?

    Don't answer that...

    November 8, 2007

  • If it isn't a federal offense, it darn well should be. Hmph.

    Skipvia, you're not alone. If you had wondered what they were for, you'd be an odd bird.


    November 8, 2007

  • WordNet is a bit different than a normal dictionary. Diamond has a general physical definition, which we all know. The term diamond is typically used to describe a piece of diamond mounted on some sort jewelry. This is the most commonly used, which is why it is the first definition WordNet gives.

    Looking at the WordNet entry should be illustrative.

    November 8, 2007

  • "She is very honest, and will be as hard to cut as a rough diamond." - 'A Wife for a Month', John Fletcher, 1624.

    December 11, 2007

  • 'I suppose it is one of Nature's positive laws, that even diamond rings, worn a while, cease to raise that glow in a lady's bosom which first possession excited.'

    'I think,' said Mrs. Sumelin, 'it is not very polite to compare a lady to a diamond ring.'

    —Robert Bage, 1796, Hermsprong

    We have probably all heard that it was a marketing campaign by De Beers in the early 1900s that made diamonds the ubiquitous engagement gift; so this quotation is a salutary antidote to thinking they must have been little used before then.

    March 21, 2009

  • Long i, monosyllabic, is represented here by -ia-. I can't think of any other words that do the same. Can anybody?

    June 7, 2010

  • In those the a's seem to create a second vowel (schwa, really) with the l's. I guess one could say that the schwa comes from the l's alone (compare homonyms vile and file) or that they aren't really disyllabic, but I don't think I would agree with either of those assertions.

    June 7, 2010

  • Sometimes liable can sound like "lye-bull" - especially, of course, when it follows reckon in a sentence such as "I reckon he's liable to stick around these here parts."

    June 8, 2010