Indigo (noun)

1. A blue dye obtained from various plants, especially Indigofera tinctoria.
2. A deep and rich shade of blue, typically considered as a color between blue and violet.

Origin:

Late 16th century: via portuguese from arabic al-nīqī "indigo", from nīq "indigo plant".

Examples:

1. The ancient Egyptians used indigo to dye their clothes.
2. The indigo dye was used to color the fabric of the curtains.
3. The indigo sky at sunset was breathtaking.
4. The artist used indigo as the main color in his painting.
5. The indigo color of the dress was beautiful and elegant.