'bacteriophage' originates from New Latin and Greek, specifically combining 'bacterio-' from New Latin 'bacterium' (meaning 'rod-shaped bacterium') and 'phage' from Greek 'phagein', where 'phagein' meant 'to eat' or 'devour'.

'bacteriophage' was coined in the early 20th century (commonly attributed to Félix d'Hérelle in 1917) by combining the element 'bacterio-' with the Greek root 'phagein'; the term entered scientific English usage to name viruses that 'eat' or destroy bacteria.

Initially, it conveyed the sense 'bacteria-eater' (a literal 'eater of bacteria'); over time it came to refer specifically to viruses that infect and often lyse bacteria, the modern scientific meaning.