About
The character 靛 is a phono-semantic compound, combining the semantic radical 青 (qīng, meaning blue, green, or cyan) on the left with the phonetic component 定 (dìng) on the right, which indicates its pronunciation. It was created to denote the deep blue dye indigo, historically extracted from plants. The color radical places its meaning firmly within the visual spectrum, and the character is used to describe this dark blue pigment in traditional textiles and as one of the primary rainbow colors, functioning both as a noun for the dye and an adjective for the hue.