diamond

Etymology 1

From Middle English dyamaunt, from Old French diamant, from Late Latin diamas, from Latin adamas, from Ancient Greek ἀδάμας (adámas, “diamond”).

noun

1. (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.
   The saw is coated with diamond.
2. A gemstone made from this mineral.
   The dozen loose diamonds sparkled in the light.
   Although there are dozens of different types of gems, among the best known and most important are diamond, ruby and sapphire, emerald and other gem forms of the mineral beryl, chrysoberyl, tanzanite, tsavorite, topaz and jade. 2012-03, Lee A. Groat, “Gemstones”, in American Scientist, volume 100, number 2, archived from the original on 2012-06-14, page 128
3. A ring containing a diamond.
   What a beautiful engagement diamond.
4. A very pale blue color.
   diamond:
5. (heraldry) Sable, when blazoning by precious stones.
   Elphingston. Pearl a Chevron Diamond between three Boars Heads Eraz'd Ruby, arm'd of the first. / Eymouth. Diamond a Lyon Rampant Pearl, on a Canton of the 2d, a Cross Ruby. 1720, Francis Nichols, Rudiments of Honour, page 296
   The Field is Ruby, on a Bend Topaz, three Martlets Diamond. The Armes of the most Noble and Puissant Lord, Edward Brabazon, Earl of Meath, and Baron of Atherdee in the Kingdom of Ireland. His Lordship's Atchievements are Quarterly of sixteen Coats. 1. Brabazon, as above. 2. Diamond, on a Chevron between three Pickaxes Pearl, as many Mullets Ruby, by the Name of Mosley. 3. Saphire, ten Bezants, 4, 3, 2, 1, by the Bisset. 1726, John Guillim, The Banner Display'd; Or, an Abridgment of Guillim, page 504
   Pearl, an Eagle, Diamond, between three Crosses Patee, Ruby, for Morrys. 1754, John Lodge, The Peerage of Ireland; Or, a Genealogical History of the ..., page 71
6. Something that resembles a diamond.
7. (geometry) A rhombus, especially when oriented so that its longer axis is vertical.
8. (geometry) The polyiamond made up of two triangles.
9. (baseball) The entire field of play used in the game.
10. (baseball) The infield of a baseball field.
    The teams met on the diamond.
11. (card games) A card of the diamonds suit.
    I have only one diamond in my hand.
12. (printing, uncountable, dated) A size of type, standardised as 4+¹⁄₂ point.

adj

1. made of, or containing diamond, a diamond or diamonds.
   He gave her diamond earrings.
2. of, relating to, or being a sixtieth anniversary.
   Today is their diamond wedding anniversary.
3. of, relating to, or being a seventy-fifth anniversary.
   Today is their diamond wedding anniversary.
4. (slang) First-rate; excellent.
   He's a diamond geezer.

verb

1. to adorn with or as if with diamonds

Etymology 2

Borrowed from Dutch diamant, used by Dirck Voskens who first cut it around 1700, presumably naming it by analogy with the larger Perl.

noun

1. (printing, dated) The size of type between brilliant and pearl, standardized as 4+¹⁄₂-point.