indigo

American  

[in-di-goh] / ˈɪn dɪˌgoʊ /

noun

plural

indigos, indigoes

1. a blue dye obtained from various plants, especially of the genus Indigofera, or manufactured synthetically.

2. indigo blue.

3. any of numerous hairy plants belonging to the genus Indigofera, of the legume family, having pinnate leaves and clusters of usually red or purple flowers.

4. a color ranging from a deep violet blue to a dark, grayish blue.

---

adjective

1. Also called indigotic.  Also called indigo-blue,.  of the color indigo.

indigo British  

/ ˈɪndɪˌɡəʊ, ˌɪndɪˈɡɒtɪk /

noun

1. Also called: indigotin.  a blue vat dye originally obtained from plants but now made synthetically

2. any of various tropical plants of the leguminous genus Indigofera, such as the anil, that yield this dye Compare wild indigo

3. 1. any of a group of colours that have the same blue-violet hue; a spectral colour

   2. ( as adjective )

      an indigo carpet

---

Other Word Forms

• indigotic
  adjective

Etymology

Origin of indigo

1545–55; < Spanish or Portuguese, variant of índico < Latin indicum < Greek indikón, noun use of neuter of Indikós Indic

Explanation

Indigo is a flowering plant that's native to Asia, and it's also the name of a deep blue dye made from the leaves of the indigo plant. You can also use the word to mean the shade of blue itself. The indigo plant is in the pea family. While this plant often has brightly colored flowers, indigo dye is traditionally made from the plant's leaves. This type of tint was once the most common natural dye in the world — though today, most of what's called indigo is synthetically made. Indigo is also one of the colors of the rainbow: red, orange, yellow, green, blue, indigo, and violet. The Greek root indikon means "blue dye from India."

Example Sentences

As the sub dropped below 200 metres, the last traces of light disappeared, and indigo faded into total darkness.

From Barron's • Jan. 26, 2026

Although a menacing observer lurks in the darkness, the couple feels protected, submerged beneath the wall of clouds, which roll like white waves against a huge, indigo sky.

From The Wall Street Journal • Nov. 15, 2025

Through the window of an upper floor office in West Hollywood, the sky changed from cyan to navy and then indigo blue.

From Los Angeles Times • Nov. 14, 2024

But over the years, indigo fell out of favour because growing the crop damaged the soil excessively.

From BBC • Oct. 16, 2024

The assembly looked with him, considered the vast stretches of water, the high sea beyond, unknown indigo of infinite possibility, heard silently the sough and whisper from the reef.

From "Lord of the Flies" by William Golding

Related Words

• blue-green