syngeneic Syllabification: (syn·ge·ne·ic)Pronunciation: /ˌsinjəˈnēik/Definition of syngeneic adjective Medicine & Biology (of organisms or cells) genetically similar or identical and hence immunologically compatible, especially so closely related that transplantation does not provoke an immune response. Origin: 1960s: from syn- 'together' + Greek genea 'race, stock' + -icsyngeneic in other Oxford dictionaries Definition of syngeneic in the British & World English dictionary