rə̇ˈketsēə noun
Etymology: New Latin, from Howard T. Ricketts died 1910 American pathologist + New Latin -ia
1. capitalized : the type genus of Rickettsiaceae comprising pleomorphic rod-shaped nonfilterable microorganisms that live intracellularly in biting arthropods and when transmitted to man by the bite of an arthropod host cause a number of serious diseases (as Rocky Mountain spotted fever and typhus)
2. plural rickettsi·ae -sēˌē or rickettsias also rickettsia sometimes capitalized : any member of the genus Rickettsia or the family Rickettsiaceae