WordNet records no synonym and no antonym for yoga. 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.
discipline aimed at training the consciousness for a state of perfect spiritual insight and tranquility that is achieved through the three paths of actions and knowledge and devotion
a system of physical, breathing and meditation exercises practiced to promote control of the body and mind
Synonyms, antonyms and the broader and narrower relations for yoga come from Princeton University’s WordNet. Full sources and licences.