nystatin n an antifungal and antibiotic (trade names Mycostatin and Nystan) discovered in New York State; derived from soil fungi actinomycetes Usage(s) In treating such cases of moniliasis, still another antibiotic has been found to help undo the harm wrought by other antibioticsnystatin (Mycostatin), which has come into . Synonym(s) Mycostatin Nystan