WordNet records no synonym and no antonym for tarsier. 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.
nocturnal arboreal primate of Indonesia and the Philippines having huge eyes and digits ending in pads to facilitate climbing; the only primate that spurns all plant material as food living entirely on insects and small vertebrates
Synonyms, antonyms and the broader and narrower relations for tarsier come from Princeton University’s WordNet. Full sources and licences.