WordNet records no synonym and no antonym for oliguria. It is the only member of each of its synsets, 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.
abnormally small production of urine; can be a symptom of kidney disease or obstruction of the urinary tract or edema or an imbalance of fluids and electrolytes in the body
production of an abnormally small amount of urine
Synonyms, antonyms and the broader and narrower relations for oliguria come from Princeton University’s WordNet. Full sources and licences.