DICT.TW Dictionary Taiwan
In·di·go n.; pl. Indigoes
1. A kind of deep blue, one of the seven prismatic colors.
2. Chem. A blue dyestuff obtained from several plants belonging to very different genera and orders, such as, the woad, Isatis tinctoria (family Cruciferae), Indigofera suffroticosa, Indigofera tinctoria (family Leguminosae), Indigofera Anil, Nereum tinctorium, Polygonum tinctorium Ait. (family Polygonaceae), etc.; called also natural indigo. It is a dark blue earthy substance, tasteless and odorless, with a copper-violet luster when rubbed. Indigo does not exist in the plants as such, but is obtained by decomposition of the glycoside indican.
Note: ☞ Commercial indigo contains the essential coloring principle indigo blue or indigotine, with several other dyes; as, indigo red, indigo brown, etc., and various impurities. Indigo is insoluble in ordinary reagents, with the exception of strong sulphuric acid.
Chinese indigo Bot., Isatis indigotica, a kind of woad.
Wild indigo Bot., the American herb Baptisia tinctoria which yields a poor quality of indigo, as do several other species of the same genus.
In·di·go a. Having the color of, pertaining to, or derived from, indigo.
Indigo berry Bot., the fruit of the West Indian shrub Randia aculeata, used as a blue dye.
Indigo bird Zool., a small North American finch (Cyanospiza cyanea). The male is indigo blue in color. Called also indigo bunting.
Indigo blue. (a) The essential coloring material of commercial indigo, from which it is obtained as a dark blue earthy powder, with a reddish luster, C16H10N2O2, which may be crystallized by sublimation. Indigo blue is also made from artificial amido cinnamic acid, and from artificial isatine; and these methods are of great commercial importance. Called also indigotin. (b) A dark, dull blue color like the indigo of commerce.
Indigo brown Chem., a brown resinous substance found in crude indigo.
Indigo copper Min., covellite.
Indigo green, a green obtained from indigo.
Indigo plant Bot., a leguminous plant of several species (genus Indigofera), from which indigo is prepared. The different varieties are natives of Asia, Africa, and America. Several species are cultivated, of which the most important are the Indigofera tinctoria, or common indigo plant, the Indigofera Anil, a larger species, and the Indigofera disperma.
Indigo purple, a purple obtained from indigo.
Indigo red, a dyestuff, isomeric with indigo blue, obtained from crude indigo as a dark brown amorphous powder.
Indigo snake Zool., the gopher snake.
Indigo white, a white crystalline powder obtained by reduction from indigo blue, and by oxidation easily changed back to it; -- called also indigogen.
Indigo yellow, a substance obtained from indigo.
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In·di·gof·e·ra n. Bot. A genus of leguminous plants (family Leguminosae) having many species, mostly in tropical countries, several of them yielding indigo, esp. Indigofera tinctoria, Indigofera suffroticosa, and Indigofera Anil.
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Indigofera tinctoria
n : deciduous subshrub of southeastern Asia having pinnate
leaves and clusters of red or purple flowers; a source of
indigo dye [syn: indigo, indigo plant]