WordNet records no synonym and no antonym for orthoepist. It is the only member of its synset, 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 practitioner of orthoepy (especially one of the 17th or 18th century scholars who proposed to reform English spelling so it would reflect pronunciation more closely)
Synonyms, antonyms and the broader and narrower relations for orthoepist come from Princeton University’s WordNet. Full sources and licences.