PathogenPronunciation/PATH-oh-jen/CategoryGeneralSingularPathogenPluralPathogensDefinitionA microorganism that causes disease.EtymologyFrom Greek 'pathos', meaning 'suffering' or 'disease', and 'genes', meaning 'origin'.ExampleThe pathogen responsible for causing malaria is a single-celled parasite.Related TermsDiseaseMicroorganismInfection