indigo (n.) Look up indigo at Dictionary.com
1550s, from Spanish indico, Portuguese endego, and Dutch (via Portuguese) indigo, all from Latin indicum "indigo," from Greek indikon "blue dye from India," literally "Indian (substance)," neuter of indikos "Indian," from India (see India). As "the color of indigo" from 1620s. Replaced Middle English ynde (late 13c., from Old French inde, from Latin indicum). Earlier name in Mediterranean languages was annil, anil (see aniline).