WordNet records no synonym and no antonym for reaumur scale. 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 temperature scale on which water freezes at 0 degrees and boils at 80 degrees
Synonyms, antonyms and the broader and narrower relations for reaumur scale come from Princeton University’s WordNet. Full sources and licences.