[in.di.go] n, pl -gos or -goes [It dial., fr. L indicum, fr. Gk indikon, fr. neut. of indikos Indic, fr. Indos India] (1555) 1 a: a blue vat dye obtained from plants (as indigo plants) b: the principal coloring matter of natural indigo usu. synthesized as a blue powder with a coppery luster
2: indigo plant
3: a deep reddish blue