pathogen Syllabification: (path·o·gen)Pronunciation: /ˈpaTHəjən, -ˌjen/Translate pathogen | into German Definition of pathogen noun Medicine a bacterium, virus, or other microorganism that can cause disease. Derivatives pathogenicPronunciation: /ˌpaTHəˈjenik/ adjective pathogenicityPronunciation: /ˌpaTHəjəˌnisitē/ noun pathogenousPronunciation: /pəˈTHäjənəs/ adjective pathogen in other Oxford dictionaries Definition of pathogen in the British & World English dictionary