indigo

n [U] 1 deep blue dye (obtained from plants) 靛, 靛青, 靛蓝（自植物中提取的颜料）. 2 its colour (in the spectrum between blue and violet) 靛蓝色: a tropical night sky of deepest indigo 靛蓝色的热带夜空. =>illus at spectrum 见spectrum插图.

indication, indicative, indicator, indices, indict, indictable, indictment, indifference, indifferent, indifferently, indigence, indigenous, indigent, indigestibility, indigestible, indigestion, indignant, indignantly, indignation, indignity, indirect, indirect object, indirect question, indirect speech (also reported speech), indirect tax, indirectly, indirectness, indiscernible, indiscipline, indiscreet, indiscreetly, indiscretion, indiscribable, indiscriminate, indiscriminately, indispensability, indispensable, indisposed, indisposition, indisputable,