indigo/ˈɪndɪgəu; `ɪndɪˌɡo/ 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.
牛津英汉双解词典