'bacteria' originates from New Latin, specifically the word 'bacterium', where the Greek word 'bakterion' meant 'small staff' or 'rod'.

'bacterium' changed from the Greek word 'bakterion' and entered scientific Latin as 'bacterium'; from New Latin the plural 'bacteria' was adopted into English to refer to these microorganisms.

Initially, it meant 'small staff' (a diminutive of a rod), but over time it evolved to refer to microscopic rod-shaped organisms and then more broadly to single-celled prokaryotic organisms.