WordNet records no synonym and no antonym for silverpoint. 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 drawing made on specially prepared paper with an instrument having a silver tip (15th and 16th centuries)
Synonyms, antonyms and the broader and narrower relations for silverpoint come from Princeton University’s WordNet. Full sources and licences.