bacteria (n.) Look up bacteria at
1847, plural of Modern Latin bacterium, from Greek bakterion "small staff," diminutive of baktron "stick, rod, staff, cudgel," from PIE *bak- "staff used for support" (also source of Latin baculum "rod, walking stick"). So called because the first ones observed were rod-shaped. Introduced as a scientific word 1838 by German naturalist Christian Gottfried Ehrenberg (1795-1876).