WordNet records no synonym and no antonym for indie. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a pop group not affiliated with a major record company
an independent film company not associated with an established studio
1 of the 3 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for indie.
Synonyms, antonyms and the broader and narrower relations for indie come from Princeton University’s WordNet. Full sources and licences.