ˌlējəˈnelə noun
Etymology: New Latin, from English legion naire + New Latin -ella
1. capitalized : a genus of gram-negative rod-shaped bacteria (family Legionellaceae) that includes the causative agent ( L. pneumophila ) of Legionnaires' disease
2. plural le·gion·el·lae -ˈne(ˌ)lē also legionellas : a bacterium of the genus Legionella