usually nonphotosynthetic free-living protozoan with whiplike appendages; some pathogens of humans and other animals whip; "The religious fanatics flagellated themselves"
() From the verb flagellate 'to lash, whip', from Latin flagellatus 'flagellated', the past participle of flagellare 'to whip', itself from flagellum, the diminutive of flagrum 'whip'