WordNet records no synonym and no antonym for essential tremor. 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.
tremor of unknown cause (usually of the hands and head) that develops in older people; often mistaken for Parkinsonism but is not life-threatening and can usually be kept under control
Synonyms, antonyms and the broader and narrower relations for essential tremor come from Princeton University’s WordNet. Full sources and licences.