pleiotropyPronunciation: /plʌɪˈɒtrəpi/Definition of pleiotropy noun [mass noun] Genetics the production by a single gene of two or more apparently unrelated effects. Derivatives pleiotropicPronunciation: /-ˈtrəʊpɪk, -ˈtrɒpɪk/ adjective pleiotropism noun Origin: 1930s: from Greek pleiōn 'more' + tropē 'turning'pleiotropy in other Oxford dictionaries Definition of pleiotropy in the US English dictionary