1 a a natural blue dye obtained from the indigo plant. b a synthetic form of this dye.
2 any plant of the genus Indigofera.
3 (in full indigo blue) a colour between blue and violet in the spectrum.
Derivatives:
indigotic adj.
Etymology: 16th-c. indico (f. Sp.), indigo (f. Port.) f. L indicum f. Gk indikon INDIAN (dye)
Useful english dictionary. 2012.