The Collaborative International Dictionary of English v.0.48:

nystatin \nystatin\ n. [From NY state + -in, due to its
   discovery in New York State.]
   An antifungal antibiotic, extracted from fermentation broths
   of the soil actinomycete Streptomyces noursei and other
   actinomycetes; called also fungicidin. It is a polyene
   macrolide antibiotic, and consists of several related
   components. Component nystatin A1 has formula C47H75NO17.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

nystatin
    n 1: an antifungal and antibiotic (trade names Mycostatin and
         Nystan) discovered in New York State; derived from soil
         fungi actinomycetes [syn: nystatin, Mycostatin,
         Nystan]