bastard indigo is a noun meaning "East Indian shrub". It carries 3 recorded senses.
East Indian shrub
dense shrub of moist riverbanks and flood plains of the eastern United States having attractive fragrant foliage and dense racemes of dark purple flowers
an erect to spreading hairy shrub of the Pacific coast of the United States having racemes of red to indigo flowers
Definitions, synonyms and semantic relations for bastard indigo come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.