WordNet records no synonym and no antonym for apparatchik. 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 humorous but derogatory term for an official of a large organization (especially a political organization)
“Democratic apparatchiks”
a communist who was a member of the administrative system of a communist party
Synonyms, antonyms and the broader and narrower relations for apparatchik come from Princeton University’s WordNet. Full sources and licences.