CIDE DICTIONARY
ultramarine, a. [Pref. ultra- + marine.].
ultramarine, n. [Cf. Sp. ultramarino. So called because the lapis lazuli was originally brought from beyond the sea, -- from Asia.].
A blue pigment formerly obtained by powdering lapis lazuli, but now produced in large quantities by fusing together silica, alumina, soda, and sulphur, thus forming a glass, colored blue by the sodium polysulphides made in the fusion. Also used adjectively. [1913 Webster]
Green ultramarine, a green pigment obtained as a first product in the manufacture of ultramarine, into which it is changed by subsequent treatment. -- Ultramarine ash or Ultramarine ashes (Paint.), a pigment which is the residuum of lapis lazuli after the ultramarine has been extracted. It was used by the old masters as a middle or neutral tint for flesh, skies, and draperies, being of a purer and tenderer gray than that produced by the mixture of more positive colors. Fairholt.
OXFORD DICTIONARY
ultramarine, n. & adj.
--n.
1 a a brilliant blue pigment orig. obtained from lapis lazuli. b an imitation of this from powdered fired clay, sodium carbonate, sulphur, and resin.
2 the colour of this.
--adj.
1 of this colour.
2 archaic situated beyond the sea.
obs. It. oltramarino & med.L ultramarinus beyond the sea (as ULTRA-, MARINE), because lapis lazuli was brought from beyond the sea
ROGET THESAURUS
ultramarine
Blueness
N
blueness, blue, garter-blue, watchet,
ultramarine, smalt, cobalt, cyanogen, Prussian blue, syenite blue, bice, indigo, zaffer, lapis lazuli, sapphire, turquoise, indicolite, blueness, bluishness, bloom, blue, azure, cerulean, sky-blue, sky-colored, sky-dyed, cerulescent, powder blue, bluish, atmospheric, retiring, cold.