'bacteriophage' originates from New Latin/modern scientific formation, combining 'bacterio-' (from New Latin 'bacterium', ultimately from Greek 'bakterion') and Greek 'phage' (from 'phagein'), where 'bakterion' meant 'small staff, rod' and 'phagein' meant 'to eat'.

'bacteriophage' was coined in the early 20th century (used and popularized by Félix d'Herelle) by combining the Neo-Latin/Greek elements 'bacterio-' + 'phage' and became the established scientific term 'bacteriophage'.

Initially, it literally meant 'bacteria-eater' (an entity that eats bacteria), but over time it came to mean specifically 'a virus that infects and replicates within bacteria'.